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CONFIG_ARM64_LSE_ATOMICS and -ffixed-REG, -fcall-used-REG, -fcall-saved-REG #25

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nickdesaulniers opened this issue Aug 2, 2018 · 4 comments
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[ARCH] arm64 This bug impacts ARCH=arm64 [BUG] linux A bug that should be fixed in the mainline kernel. [BUG] llvm A bug that should be fixed in upstream LLVM [FIXED][LINUX] 4.20 This bug was fixed in Linux 4.20 [FIXED][LLVM] 8 This bug was fixed in LLVM 8.0

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nickdesaulniers commented Aug 2, 2018

CONFIG_ARM64_LSE_ATOMICS is now on by default for arm64's defconfig. This currently requires the compiler flags -ffixed-REG, -fcall-used-REG, -fcall-saved-REG.

llvm bug: https://llvm.org/pr9457
llvm patch with relevant discusson: https://reviews.llvm.org/D48580#1173710
CrOS bug: https://bugs.chromium.org/p/chromium/issues/detail?id=865188

We should either implement these flags in LLVM, or come up with a suitable kernel path (or maybe some combination of both).

@nickdesaulniers nickdesaulniers modified the milestone: ARCH=arm64 defconfig Aug 2, 2018
@nickdesaulniers nickdesaulniers added the [ARCH] arm64 This bug impacts ARCH=arm64 label Aug 3, 2018
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nickdesaulniers commented Sep 7, 2018

@nickdesaulniers nickdesaulniers added [BUG] llvm A bug that should be fixed in upstream LLVM and removed [BUG] Untriaged Something isn't working [PATCH] Does not exist (yet) labels Sep 11, 2018
@nickdesaulniers nickdesaulniers added this to the ARCH=arm64 allyesconfig milestone Sep 11, 2018
@nickdesaulniers nickdesaulniers added [PATCH] Accepted A submitted patch has been accepted upstream [PATCH] Exists There is a patch that fixes this issue [BUG] linux A bug that should be fixed in the mainline kernel. labels Sep 23, 2018
nickdesaulniers pushed a commit that referenced this issue Sep 24, 2018
Chen Yu reported a divide-by-zero error when accessing the 'size'
resctrl file when a MBA resource is enabled.

divide error: 0000 [#1] SMP PTI
CPU: 93 PID: 1929 Comm: cat Not tainted 4.19.0-rc2-debug-rdt+ #25
RIP: 0010:rdtgroup_cbm_to_size+0x7e/0xa0
Call Trace:
rdtgroup_size_show+0x11a/0x1d0
seq_read+0xd8/0x3b0

Quoting Chen Yu's report: This is because for MB resource, the
r->cache.cbm_len is zero, thus calculating size in rdtgroup_cbm_to_size()
will trigger the exception.

Fix this issue in the 'size' file by getting correct memory bandwidth value
which is in MBps when MBA software controller is enabled or in percentage
when MBA software controller is disabled.

Fixes: d9b48c8 ("x86/intel_rdt: Display resource groups' allocations in bytes")
Reported-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Chen Yu <yu.c.chen@intel.com>
Cc: "H Peter Anvin" <hpa@zytor.com>
Cc: "Tony Luck" <tony.luck@intel.com>
Cc: "Xiaochen Shen" <xiaochen.shen@intel.com>
Link: https://lkml.kernel.org/r/20180904174614.26682-1-yu.c.chen@intel.com
Link: https://lkml.kernel.org/r/1537048707-76280-3-git-send-email-fenghua.yu@intel.com
@nickdesaulniers nickdesaulniers added [FIXED][LLVM] 8 This bug was fixed in LLVM 8.0 [FIXED][LINUX] 4.20 This bug was fixed in Linux 4.20 labels Sep 25, 2018
@tpimh tpimh removed [PATCH] Accepted A submitted patch has been accepted upstream [PATCH] Exists There is a patch that fixes this issue labels Sep 25, 2018
nathanchance pushed a commit that referenced this issue Oct 5, 2018
Add missing prepare/unprepare operations for fbi->clk,
this fixes following kernel warning:

  ------------[ cut here ]------------
  WARNING: CPU: 0 PID: 1 at drivers/clk/clk.c:874 clk_core_enable+0x2c/0x1b0
  Enabling unprepared disp0_clk
  Modules linked in:
  CPU: 0 PID: 1 Comm: swapper Not tainted 4.18.0-rc8-00032-g02b43ddd4f21-dirty #25
  Hardware name: Marvell MMP2 (Device Tree Support)
  [<c010f7cc>] (unwind_backtrace) from [<c010cc6c>] (show_stack+0x10/0x14)
  [<c010cc6c>] (show_stack) from [<c011dab4>] (__warn+0xd8/0xf0)
  [<c011dab4>] (__warn) from [<c011db10>] (warn_slowpath_fmt+0x44/0x6c)
  [<c011db10>] (warn_slowpath_fmt) from [<c043898c>] (clk_core_enable+0x2c/0x1b0)
  [<c043898c>] (clk_core_enable) from [<c0439ec8>] (clk_core_enable_lock+0x18/0x2c)
  [<c0439ec8>] (clk_core_enable_lock) from [<c0436698>] (pxa168fb_probe+0x464/0x6ac)
  [<c0436698>] (pxa168fb_probe) from [<c04779a0>] (platform_drv_probe+0x48/0x94)
  [<c04779a0>] (platform_drv_probe) from [<c0475bec>] (driver_probe_device+0x328/0x470)
  [<c0475bec>] (driver_probe_device) from [<c0475de4>] (__driver_attach+0xb0/0x124)
  [<c0475de4>] (__driver_attach) from [<c0473c38>] (bus_for_each_dev+0x64/0xa0)
  [<c0473c38>] (bus_for_each_dev) from [<c0474ee0>] (bus_add_driver+0x1b8/0x230)
  [<c0474ee0>] (bus_add_driver) from [<c0476a20>] (driver_register+0xac/0xf0)
  [<c0476a20>] (driver_register) from [<c0102dd4>] (do_one_initcall+0xb8/0x1f0)
  [<c0102dd4>] (do_one_initcall) from [<c0b010a0>] (kernel_init_freeable+0x294/0x2e0)
  [<c0b010a0>] (kernel_init_freeable) from [<c07e9eb8>] (kernel_init+0x8/0x10c)
  [<c07e9eb8>] (kernel_init) from [<c01010e8>] (ret_from_fork+0x14/0x2c)
  Exception stack(0xd008bfb0 to 0xd008bff8)
  bfa0:                                     00000000 00000000 00000000 00000000
  bfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
  bfe0: 00000000 00000000 00000000 00000000 00000013 00000000
  ---[ end trace c0af40f9e2ed7cb4 ]---

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
[b.zolnierkie: enhance patch description a bit]
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
@nickdesaulniers nickdesaulniers added the Needs Backport Should be backported to either linux-stable tree or latest llvm release branch. label Oct 10, 2018
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Reopening to asses whether Tri's kernel patch needs backporting to kernel LTS branches.

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nickdesaulniers commented Oct 29, 2018

https://lore.kernel.org/r/20181029170822.234795-1-ndesaulniers@google.com/: [PATCH] kbuild: set no-integrated-as before incl. arch Makefile
https://lore.kernel.org/r/20181029171026.236752-1-ndesaulniers@google.com/: [PATCH] arm64: lse: remove -fcall-used-x0 flag

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nickdesaulniers commented Oct 29, 2018

@agners noted that the first is already queued: https://lore.kernel.org/r/6c945975fbf9ff68dad29e42f0c030c5@agner.ch/

nathanchance pushed a commit that referenced this issue Nov 9, 2018
Increase kasan instrumented kernel stack size from 32k to 64k. Other
architectures seems to get away with just doubling kernel stack size under
kasan, but on s390 this appears to be not enough due to bigger frame size.
The particular pain point is kasan inlined checks (CONFIG_KASAN_INLINE
vs CONFIG_KASAN_OUTLINE). With inlined checks one particular case hitting
stack overflow is fs sync on xfs filesystem:

 #0 [9a0681e8]  704 bytes  check_usage at 34b1fc
 #1 [9a0684a8]  432 bytes  check_usage at 34c710
 #2 [9a068658]  1048 bytes  validate_chain at 35044a
 #3 [9a068a70]  312 bytes  __lock_acquire at 3559fe
 #4 [9a068ba8]  440 bytes  lock_acquire at 3576ee
 #5 [9a068d60]  104 bytes  _raw_spin_lock at 21b44e0
 #6 [9a068dc8]  1992 bytes  enqueue_entity at 2dbf72
 #7 [9a069590]  1496 bytes  enqueue_task_fair at 2df5f0
 #8 [9a069b68]  64 bytes  ttwu_do_activate at 28f438
 #9 [9a069ba8]  552 bytes  try_to_wake_up at 298c4c
 #10 [9a069dd0]  168 bytes  wake_up_worker at 23f97c
 #11 [9a069e78]  200 bytes  insert_work at 23fc2e
 #12 [9a069f40]  648 bytes  __queue_work at 2487c0
 #13 [9a06a1c8]  200 bytes  __queue_delayed_work at 24db28
 #14 [9a06a290]  248 bytes  mod_delayed_work_on at 24de84
 #15 [9a06a388]  24 bytes  kblockd_mod_delayed_work_on at 153e2a0
 #16 [9a06a3a0]  288 bytes  __blk_mq_delay_run_hw_queue at 158168c
 #17 [9a06a4c0]  192 bytes  blk_mq_run_hw_queue at 1581a3c
 #18 [9a06a580]  184 bytes  blk_mq_sched_insert_requests at 15a2192
 #19 [9a06a638]  1024 bytes  blk_mq_flush_plug_list at 1590f3a
 #20 [9a06aa38]  704 bytes  blk_flush_plug_list at 1555028
 #21 [9a06acf8]  320 bytes  schedule at 219e476
 #22 [9a06ae38]  760 bytes  schedule_timeout at 21b0aac
 #23 [9a06b130]  408 bytes  wait_for_common at 21a1706
 #24 [9a06b2c8]  360 bytes  xfs_buf_iowait at fa1540
 #25 [9a06b430]  256 bytes  __xfs_buf_submit at fadae6
 #26 [9a06b530]  264 bytes  xfs_buf_read_map at fae3f6
 #27 [9a06b638]  656 bytes  xfs_trans_read_buf_map at 10ac9a8
 #28 [9a06b8c8]  304 bytes  xfs_btree_kill_root at e72426
 #29 [9a06b9f8]  288 bytes  xfs_btree_lookup_get_block at e7bc5e
 #30 [9a06bb18]  624 bytes  xfs_btree_lookup at e7e1a6
 #31 [9a06bd88]  2664 bytes  xfs_alloc_ag_vextent_near at dfa070
 #32 [9a06c7f0]  144 bytes  xfs_alloc_ag_vextent at dff3ca
 #33 [9a06c880]  1128 bytes  xfs_alloc_vextent at e05fce
 #34 [9a06cce8]  584 bytes  xfs_bmap_btalloc at e58342
 #35 [9a06cf30]  1336 bytes  xfs_bmapi_write at e618de
 #36 [9a06d468]  776 bytes  xfs_iomap_write_allocate at ff678e
 #37 [9a06d770]  720 bytes  xfs_map_blocks at f82af8
 #38 [9a06da40]  928 bytes  xfs_writepage_map at f83cd6
 #39 [9a06dde0]  320 bytes  xfs_do_writepage at f85872
 #40 [9a06df20]  1320 bytes  write_cache_pages at 73dfe8
 #41 [9a06e448]  208 bytes  xfs_vm_writepages at f7f892
 #42 [9a06e518]  88 bytes  do_writepages at 73fe6a
 #43 [9a06e570]  872 bytes  __writeback_single_inode at a20cb6
 #44 [9a06e8d8]  664 bytes  writeback_sb_inodes at a23be2
 #45 [9a06eb70]  296 bytes  __writeback_inodes_wb at a242e0
 #46 [9a06ec98]  928 bytes  wb_writeback at a2500e
 #47 [9a06f038]  848 bytes  wb_do_writeback at a260ae
 #48 [9a06f388]  536 bytes  wb_workfn at a28228
 #49 [9a06f5a0]  1088 bytes  process_one_work at 24a234
 #50 [9a06f9e0]  1120 bytes  worker_thread at 24ba26
 #51 [9a06fe40]  104 bytes  kthread at 26545a
 #52 [9a06fea8]             kernel_thread_starter at 21b6b62

To be able to increase the stack size to 64k reuse LLILL instruction
in __switch_to function to load 64k - STACK_FRAME_OVERHEAD - __PT_SIZE
(65192) value as unsigned.

Reported-by: Benjamin Block <bblock@linux.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
@nickdesaulniers nickdesaulniers removed the Needs Backport Should be backported to either linux-stable tree or latest llvm release branch. label Dec 11, 2018
nathanchance pushed a commit that referenced this issue Dec 20, 2018
create_ctx can be called from atomic context, hence use
GFP_ATOMIC instead of GFP_KERNEL.

[  395.962599] BUG: sleeping function called from invalid context at mm/slab.h:421
[  395.979896] in_atomic(): 1, irqs_disabled(): 0, pid: 16254, name: openssl
[  395.996564] 2 locks held by openssl/16254:
[  396.010492]  #0: 00000000347acb52 (sk_lock-AF_INET){+.+.}, at: do_tcp_setsockopt.isra.44+0x13b/0x9a0
[  396.029838]  #1: 000000006c9552b5 (device_spinlock){+...}, at: tls_init+0x1d/0x280
[  396.047675] CPU: 5 PID: 16254 Comm: openssl Tainted: G           O      4.20.0-rc6+ #25
[  396.066019] Hardware name: Supermicro X10SRA-F/X10SRA-F, BIOS 2.0c 09/25/2017
[  396.083537] Call Trace:
[  396.096265]  dump_stack+0x5e/0x8b
[  396.109876]  ___might_sleep+0x216/0x250
[  396.123940]  kmem_cache_alloc_trace+0x1b0/0x240
[  396.138800]  create_ctx+0x1f/0x60
[  396.152504]  tls_init+0xbd/0x280
[  396.166135]  tcp_set_ulp+0x191/0x2d0
[  396.180035]  ? tcp_set_ulp+0x2c/0x2d0
[  396.193960]  do_tcp_setsockopt.isra.44+0x148/0x9a0
[  396.209013]  __sys_setsockopt+0x7c/0xe0
[  396.223054]  __x64_sys_setsockopt+0x20/0x30
[  396.237378]  do_syscall_64+0x4a/0x180
[  396.251200]  entry_SYSCALL_64_after_hwframe+0x49/0xbe

Fixes: df9d4a1 ("net/tls: sleeping function from invalid context")
Signed-off-by: Ganesh Goudar <ganeshgr@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
nathanchance pushed a commit that referenced this issue Jan 21, 2019
…s while handle_mm_fault

do_page_fault() forgot to relinquish mmap_sem if a signal came while
handling handle_mm_fault() - due to say a ctl+c or oom etc.
This would later cause a deadlock by acquiring it twice.

This came to light when running libc testsuite tst-tls3-malloc test but
is likely also the cause for prior seen LTP failures. Using lockdep
clearly showed what the issue was.

| # while true; do ./tst-tls3-malloc ; done
| Didn't expect signal from child: got `Segmentation fault'
| ^C
| ============================================
| WARNING: possible recursive locking detected
| 4.17.0+ #25 Not tainted
| --------------------------------------------
| tst-tls3-malloc/510 is trying to acquire lock:
| 606c7728 (&mm->mmap_sem){++++}, at: __might_fault+0x28/0x5c
|
|but task is already holding lock:
|606c7728 (&mm->mmap_sem){++++}, at: do_page_fault+0x9c/0x2a0
|
| other info that might help us debug this:
|  Possible unsafe locking scenario:
|
|       CPU0
|       ----
|  lock(&mm->mmap_sem);
|  lock(&mm->mmap_sem);
|
| *** DEADLOCK ***
|

------------------------------------------------------------
What the change does is not obvious (note to myself)

prior code was

| do_page_fault
|
|   down_read()		<-- lock taken
|   handle_mm_fault	<-- signal pending as this runs
|   if fatal_signal_pending
|       if VM_FAULT_ERROR
|           up_read
|       if user_mode
|          return	<-- lock still held, this was the BUG

New code

| do_page_fault
|
|   down_read()		<-- lock taken
|   handle_mm_fault	<-- signal pending as this runs
|   if fatal_signal_pending
|       if VM_FAULT_RETRY
|          return       <-- not same case as above, but still OK since
|                           core mm already relinq lock for FAULT_RETRY
|    ...
|
|   < Now falls through for bug case above >
|
|   up_read()		<-- lock relinquished

Cc: stable@vger.kernel.org
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
nathanchance pushed a commit that referenced this issue Feb 9, 2019
Eric Biggers reported:
> The following commit, which went into v4.20, introduced undefined behavior when
> sys_rt_sigqueueinfo() is called with sig=0:
>
> commit 4ce5f9c
> Author: Eric W. Biederman <ebiederm@xmission.com>
> Date:   Tue Sep 25 12:59:31 2018 +0200
>
>     signal: Use a smaller struct siginfo in the kernel
>
> In sig_specific_sicodes(), used from known_siginfo_layout(), the expression
> '1ULL << ((sig)-1)' is undefined as it evaluates to 1ULL << 4294967295.
>
> Reproducer:
>
> #include <signal.h>
> #include <sys/syscall.h>
> #include <unistd.h>
>
> int main(void)
> {
> 	siginfo_t si = { .si_code = 1 };
> 	syscall(__NR_rt_sigqueueinfo, 0, 0, &si);
> }
>
> UBSAN report for v5.0-rc1:
>
> UBSAN: Undefined behaviour in kernel/signal.c:2946:7
> shift exponent 4294967295 is too large for 64-bit type 'long unsigned int'
> CPU: 2 PID: 346 Comm: syz_signal Not tainted 5.0.0-rc1 #25
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
> Call Trace:
>  __dump_stack lib/dump_stack.c:77 [inline]
>  dump_stack+0x70/0xa5 lib/dump_stack.c:113
>  ubsan_epilogue+0xd/0x40 lib/ubsan.c:159
>  __ubsan_handle_shift_out_of_bounds+0x12c/0x170 lib/ubsan.c:425
>  known_siginfo_layout+0xae/0xe0 kernel/signal.c:2946
>  post_copy_siginfo_from_user kernel/signal.c:3009 [inline]
>  __copy_siginfo_from_user+0x35/0x60 kernel/signal.c:3035
>  __do_sys_rt_sigqueueinfo kernel/signal.c:3553 [inline]
>  __se_sys_rt_sigqueueinfo kernel/signal.c:3549 [inline]
>  __x64_sys_rt_sigqueueinfo+0x31/0x70 kernel/signal.c:3549
>  do_syscall_64+0x4c/0x1b0 arch/x86/entry/common.c:290
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x433639
> Code: c4 18 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b 27 00 00 c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007fffcb289fc8 EFLAGS: 00000246 ORIG_RAX: 0000000000000081
> RAX: ffffffffffffffda RBX: 00000000004002e0 RCX: 0000000000433639
> RDX: 00007fffcb289fd0 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: 00000000006b2018 R08: 000000000000004d R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401560
> R13: 00000000004015f0 R14: 0000000000000000 R15: 0000000000000000

I have looked at the other callers of siginmask and they all appear to
in locations where sig can not be zero.

I have looked at the code generation of adding an extra test against
zero and gcc was able with a simple decrement instruction to combine
the two tests together. So the at most adding this test cost a single
cpu cycle.  In practice that decrement instruction was already present
as part of the mask comparison, so the only change was when the
instruction was executed.

So given that it is cheap, and obviously correct to update siginmask
to verify the signal is not zero.  Fix this issue there to avoid any
future problems.

Reported-by: Eric Biggers <ebiggers@kernel.org>
Fixes: 4ce5f9c ("signal: Use a smaller struct siginfo in the kernel")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
nathanchance pushed a commit that referenced this issue Jul 13, 2019
KASAN report this:

BUG: unable to handle kernel paging request at ffffffffa0097000
PGD 3870067 P4D 3870067 PUD 3871063 PMD 2326e2067 PTE 0
Oops: 0000 [#1
CPU: 0 PID: 5340 Comm: modprobe Not tainted 5.1.0-rc7+ #25
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/2014
RIP: 0010:__list_add_valid+0x10/0x70
Code: c3 48 8b 06 55 48 89 e5 5d 48 39 07 0f 94 c0 0f b6 c0 c3 90 90 90 90 90 90 90 55 48 89 d0 48 8b 52 08 48 89 e5 48 39 f2 75 19 <48> 8b 32 48 39 f0 75 3a

RSP: 0018:ffffc90000e23c68 EFLAGS: 00010246
RAX: ffffffffa00ad000 RBX: ffffffffa009d000 RCX: 0000000000000000
RDX: ffffffffa0097000 RSI: ffffffffa0097000 RDI: ffffffffa009d000
RBP: ffffc90000e23c68 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffffa0097000
R13: ffff888231797180 R14: 0000000000000000 R15: ffffc90000e23e78
FS:  00007fb215285540(0000) GS:ffff888237a00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffa0097000 CR3: 000000022f144000 CR4: 00000000000006f0
Call Trace:
 v9fs_register_trans+0x2f/0x60 [9pnet
 ? 0xffffffffa0087000
 p9_virtio_init+0x25/0x1000 [9pnet_virtio
 do_one_initcall+0x6c/0x3cc
 ? kmem_cache_alloc_trace+0x248/0x3b0
 do_init_module+0x5b/0x1f1
 load_module+0x1db1/0x2690
 ? m_show+0x1d0/0x1d0
 __do_sys_finit_module+0xc5/0xd0
 __x64_sys_finit_module+0x15/0x20
 do_syscall_64+0x6b/0x1d0
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7fb214d8e839
Code: 00 f3 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01

RSP: 002b:00007ffc96554278 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
RAX: ffffffffffffffda RBX: 000055e67eed2aa0 RCX: 00007fb214d8e839
RDX: 0000000000000000 RSI: 000055e67ce95c2e RDI: 0000000000000003
RBP: 000055e67ce95c2e R08: 0000000000000000 R09: 000055e67eed2aa0
R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000
R13: 000055e67eeda500 R14: 0000000000040000 R15: 000055e67eed2aa0
Modules linked in: 9pnet_virtio(+) 9pnet gre rfkill vmw_vsock_virtio_transport_common vsock [last unloaded: 9pnet_virtio
CR2: ffffffffa0097000
---[ end trace 4a52bb13ff07b761

If register_virtio_driver() fails in p9_virtio_init,
we should call v9fs_unregister_trans() to do cleanup.

Link: http://lkml.kernel.org/r/20190430115942.41840-1-yuehaibing@huawei.com
Cc: stable@vger.kernel.org
Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: b530cc7 ("9p: add virtio transport")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
nathanchance pushed a commit that referenced this issue Sep 18, 2019
syzbot reports an error on flush_request_modules() for the second device.
This workqueue was never initialised so simply remove the offending line.

usb 1-1: USB disconnect, device number 2
em28xx 1-1:1.153: Disconnecting em28xx #1
------------[ cut here ]------------
WARNING: CPU: 0 PID: 12 at kernel/workqueue.c:3031
__flush_work.cold+0x2c/0x36 kernel/workqueue.c:3031
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.3.0-rc2+ #25
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Workqueue: usb_hub_wq hub_event
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0xca/0x13e lib/dump_stack.c:113
  panic+0x2a3/0x6da kernel/panic.c:219
  __warn.cold+0x20/0x4a kernel/panic.c:576
  report_bug+0x262/0x2a0 lib/bug.c:186
  fixup_bug arch/x86/kernel/traps.c:179 [inline]
  fixup_bug arch/x86/kernel/traps.c:174 [inline]
  do_error_trap+0x12b/0x1e0 arch/x86/kernel/traps.c:272
  do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:291
  invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1026
RIP: 0010:__flush_work.cold+0x2c/0x36 kernel/workqueue.c:3031
Code: 9a 22 00 48 c7 c7 20 e4 c5 85 e8 d9 3a 0d 00 0f 0b 45 31 e4 e9 98 86
ff ff e8 51 9a 22 00 48 c7 c7 20 e4 c5 85 e8 be 3a 0d 00 <0f> 0b 45 31 e4
e9 7d 86 ff ff e8 36 9a 22 00 48 c7 c7 20 e4 c5 85
RSP: 0018:ffff8881da20f720 EFLAGS: 00010286
RAX: 0000000000000024 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8128a0fd RDI: ffffed103b441ed6
RBP: ffff8881da20f888 R08: 0000000000000024 R09: fffffbfff11acd9a
R10: fffffbfff11acd99 R11: ffffffff88d66ccf R12: 0000000000000000
R13: 0000000000000001 R14: ffff8881c6685df8 R15: ffff8881d2a85b78
  flush_request_modules drivers/media/usb/em28xx/em28xx-cards.c:3325 [inline]
  em28xx_usb_disconnect.cold+0x280/0x2a6
drivers/media/usb/em28xx/em28xx-cards.c:4023
  usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423
  __device_release_driver drivers/base/dd.c:1120 [inline]
  device_release_driver_internal+0x404/0x4c0 drivers/base/dd.c:1151
  bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:556
  device_del+0x420/0xb10 drivers/base/core.c:2288
  usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
  usb_disconnect+0x284/0x8d0 drivers/usb/core/hub.c:2199
  hub_port_connect drivers/usb/core/hub.c:4949 [inline]
  hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
  port_event drivers/usb/core/hub.c:5359 [inline]
  hub_event+0x1454/0x3640 drivers/usb/core/hub.c:5441
  process_one_work+0x92b/0x1530 kernel/workqueue.c:2269
  process_scheduled_works kernel/workqueue.c:2331 [inline]
  worker_thread+0x7ab/0xe20 kernel/workqueue.c:2417
  kthread+0x318/0x420 kernel/kthread.c:255
  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Kernel Offset: disabled
Rebooting in 86400 seconds..

Fixes: be7fd3c ("media: em28xx: Hauppauge DualHD second tuner functionality)
Reviewed-by: Ezequiel Garcia <ezequiel@collabora.com>
Reviewed-by: Brad Love <brad@nextdimension.cc>
Reported-by: syzbot+b7f57261c521087d89bb@syzkaller.appspotmail.com
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
nathanchance pushed a commit that referenced this issue Nov 26, 2019
Fix the following checkpatch errors:

$ ./scripts/checkpatch.pl --no-tree -f arch/mips/generic/init.c
ERROR: Use of const init definition must use __initconst
#23: FILE: arch/mips/generic/init.c:23:
+static __initdata const void *fdt;

ERROR: Use of const init definition must use __initconst
#24: FILE: arch/mips/generic/init.c:24:
+static __initdata const struct mips_machine *mach;

ERROR: Use of const init definition must use __initconst
#25: FILE: arch/mips/generic/init.c:25:
+static __initdata const void *mach_match_data;

Fixes: eed0eab ("MIPS: generic: Introduce generic DT-based board support")
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: ralf@linux-mips.org
Cc: jhogan@kernel.org
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
nathanchance pushed a commit that referenced this issue Nov 28, 2019
The hidden aliasing-ppgtt's size is never revealed, as we only inspect
the front GTT when engaged. However, we were "fixing" the hidden ppgtt
to match, with the net result that we ended up leaking the unused
portion on Braswell were we preallocated the entire set of top level
PDP, see gen8_preallocate_top_level_pdp().

[   26.025364] DMA-API: pci 0000:00:02.0: device driver has pending DMA allocations while released from device [count=2]
[   26.025364] One of leaked entries details: [device address=0x0000000230778000] [size=4096 bytes] [mapped with DMA_BIDIRECTIONAL] [mapped as single]
[   26.025683] WARNING: CPU: 0 PID: 415 at kernel/dma/debug.c:894 dma_debug_device_change+0x1a4/0x1f0
[   26.025905] Modules linked in: i915(E-) intel_powerclamp(E) nls_ascii(E) nls_cp437(E) crct10dif_pclmul(E) crc32_pclmul(E) vfat(E) crc32c_intel(E) fat(E) ghash_clmulni_intel(E) prime_numbers(E) intel_gtt(E) i2c_algo_bit(E) efi_pstore(E) drm_kms_helper(E) syscopyarea(E) sysfillrect(E) sysimgblt(E) fb_sys_fops(E) evdev(E) drm(E) aesni_intel(E) glue_helper(E) crypto_simd(E) cryptd(E) intel_cstate(E) sg(E) efivars(E) pcspkr(E) video(E) button(E) efivarfs(E) ip_tables(E) x_tables(E) autofs4(E) sd_mod(E) lpc_ich(E) ahci(E) mfd_core(E) i2c_i801(E) libahci(E) i2c_designware_pci(E) i2c_designware_core(E)
[   26.026613] CPU: 0 PID: 415 Comm: rmmod Tainted: G            E     5.4.0-rc6+ #25
[   26.026837] Hardware name:  /, BIOS PYBSWCEL.86A.0027.2015.0507.1758 05/07/2015
[   26.027080] RIP: 0010:dma_debug_device_change+0x1a4/0x1f0
[   26.027319] Code: 89 54 24 08 e8 ad 60 62 00 48 8b 54 24 08 48 89 c6 41 57 4d 89 e9 49 89 d8 44 89 f1 41 54 48 c7 c7 e0 61 06 82 e8 c1 aa f5 ff <0f> 0b 5a 59 48 83 3c 24 00 0f 85 97 26 00 00 8b 05 77 47 92 01 85
[   26.027600] RSP: 0018:ffff888228d2fcc8 EFLAGS: 00010282
[   26.027831] RAX: 0000000000000000 RBX: 0000000230778000 RCX: 0000000000000000
[   26.028053] RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffffed10451a5f8f
[   26.028279] RBP: ffff88823480c0b0 R08: 0000000000000001 R09: ffffed1046e83eb1
[   26.028500] R10: ffffed1046e83eb0 R11: ffff88823741f587 R12: ffffffff82067340
[   26.028725] R13: 0000000000001000 R14: 0000000000000002 R15: ffffffff82067480
[   26.028952] FS:  00007fdf3ed174c0(0000) GS:ffff888237400000(0000) knlGS:0000000000000000
[   26.029185] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   26.029405] CR2: 000055e211109030 CR3: 0000000230139000 CR4: 00000000001006f0
[   26.029622] Call Trace:
[   26.029846]  notifier_call_chain+0x67/0xa0
[   26.030076]  blocking_notifier_call_chain+0x5a/0x80
[   26.030305]  device_release_driver_internal+0x20d/0x260
[   26.030535]  driver_detach+0x7b/0xe1
[   26.030761]  bus_remove_driver+0x8c/0x153
[   26.030993]  pci_unregister_driver+0x2d/0xf0
[   26.032603]  i915_exit+0x16/0x1c [i915]

Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Fixes: 1eda701 ("drm/i915/gtt: Recursive cleanup for gen8")
References: c082afa ("drm/i915: Move aliasing_ppgtt underneath its i915_ggtt")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191106221223.7437-1-chris@chris-wilson.co.uk
(cherry picked from commit 2b0a4fc)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
nathanchance pushed a commit that referenced this issue Dec 31, 2019
In a case when a ptp chardev (like /dev/ptp0) is open but an underlying
device is removed, closing this file leads to a race. This reproduces
easily in a kvm virtual machine:

ts# cat openptp0.c
int main() { ... fp = fopen("/dev/ptp0", "r"); ... sleep(10); }
ts# uname -r
5.5.0-rc3-46cf053e
ts# cat /proc/cmdline
... slub_debug=FZP
ts# modprobe ptp_kvm
ts# ./openptp0 &
[1] 670
opened /dev/ptp0, sleeping 10s...
ts# rmmod ptp_kvm
ts# ls /dev/ptp*
ls: cannot access '/dev/ptp*': No such file or directory
ts# ...woken up
[   48.010809] general protection fault: 0000 [#1] SMP
[   48.012502] CPU: 6 PID: 658 Comm: openptp0 Not tainted 5.5.0-rc3-46cf053e #25
[   48.014624] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), ...
[   48.016270] RIP: 0010:module_put.part.0+0x7/0x80
[   48.017939] RSP: 0018:ffffb3850073be00 EFLAGS: 00010202
[   48.018339] RAX: 000000006b6b6b6b RBX: 6b6b6b6b6b6b6b6b RCX: ffff89a476c00ad0
[   48.018936] RDX: fffff65a08d3ea08 RSI: 0000000000000247 RDI: 6b6b6b6b6b6b6b6b
[   48.019470] ...                                              ^^^ a slub poison
[   48.023854] Call Trace:
[   48.024050]  __fput+0x21f/0x240
[   48.024288]  task_work_run+0x79/0x90
[   48.024555]  do_exit+0x2af/0xab0
[   48.024799]  ? vfs_write+0x16a/0x190
[   48.025082]  do_group_exit+0x35/0x90
[   48.025387]  __x64_sys_exit_group+0xf/0x10
[   48.025737]  do_syscall_64+0x3d/0x130
[   48.026056]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[   48.026479] RIP: 0033:0x7f53b12082f6
[   48.026792] ...
[   48.030945] Modules linked in: ptp i6300esb watchdog [last unloaded: ptp_kvm]
[   48.045001] Fixing recursive fault but reboot is needed!

This happens in:

static void __fput(struct file *file)
{   ...
    if (file->f_op->release)
        file->f_op->release(inode, file); <<< cdev is kfree'd here
    if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL &&
             !(mode & FMODE_PATH))) {
        cdev_put(inode->i_cdev); <<< cdev fields are accessed here

Namely:

__fput()
  posix_clock_release()
    kref_put(&clk->kref, delete_clock) <<< the last reference
      delete_clock()
        delete_ptp_clock()
          kfree(ptp) <<< cdev is embedded in ptp
  cdev_put
    module_put(p->owner) <<< *p is kfree'd, bang!

Here cdev is embedded in posix_clock which is embedded in ptp_clock.
The race happens because ptp_clock's lifetime is controlled by two
refcounts: kref and cdev.kobj in posix_clock. This is wrong.

Make ptp_clock's sysfs device a parent of cdev with cdev_device_add()
created especially for such cases. This way the parent device with its
ptp_clock is not released until all references to the cdev are released.
This adds a requirement that an initialized but not exposed struct
device should be provided to posix_clock_register() by a caller instead
of a simple dev_t.

This approach was adopted from the commit 72139df ("watchdog: Fix
the race between the release of watchdog_core_data and cdev"). See
details of the implementation in the commit 233ed09 ("chardev: add
helper function to register char devs with a struct device").

Link: https://lore.kernel.org/linux-fsdevel/20191125125342.6189-1-vdronov@redhat.com/T/#u
Analyzed-by: Stephen Johnston <sjohnsto@redhat.com>
Analyzed-by: Vern Lovejoy <vlovejoy@redhat.com>
Signed-off-by: Vladis Dronov <vdronov@redhat.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
nathanchance pushed a commit that referenced this issue Mar 31, 2020
When mmap2 events are synthesized the ino_generation field isn't being
set leading to uninitialized memory being compared.

Caught with clang's -fsanitize=memory:

==124733==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x55a96a6a65cc in __dso_id__cmp tools/perf/util/dsos.c:23:6
    #1 0x55a96a6a81d5 in dso_id__cmp tools/perf/util/dsos.c:38:9
    #2 0x55a96a6a717f in __dso__cmp_long_name tools/perf/util/dsos.c:74:15
    #3 0x55a96a6a6c4c in __dsos__findnew_link_by_longname_id tools/perf/util/dsos.c:106:12
    #4 0x55a96a6a851e in __dsos__findnew_by_longname_id tools/perf/util/dsos.c:178:9
    #5 0x55a96a6a7798 in __dsos__find_id tools/perf/util/dsos.c:191:9
    #6 0x55a96a6a7b57 in __dsos__findnew_id tools/perf/util/dsos.c:251:20
    #7 0x55a96a6a7a57 in dsos__findnew_id tools/perf/util/dsos.c:259:17
    #8 0x55a96a7776ae in machine__findnew_dso_id tools/perf/util/machine.c:2709:9
    #9 0x55a96a77dfcf in map__new tools/perf/util/map.c:193:10
    #10 0x55a96a77240a in machine__process_mmap2_event tools/perf/util/machine.c:1670:8
    #11 0x55a96a7741a3 in machine__process_event tools/perf/util/machine.c:1882:9
    #12 0x55a96a6aee39 in perf_event__process tools/perf/util/event.c:454:9
    #13 0x55a96a87d633 in perf_tool__process_synth_event tools/perf/util/synthetic-events.c:63:9
    #14 0x55a96a87f131 in perf_event__synthesize_mmap_events tools/perf/util/synthetic-events.c:403:7
    #15 0x55a96a8815d6 in __event__synthesize_thread tools/perf/util/synthetic-events.c:548:9
    #16 0x55a96a882bff in __perf_event__synthesize_threads tools/perf/util/synthetic-events.c:681:3
    #17 0x55a96a881ec2 in perf_event__synthesize_threads tools/perf/util/synthetic-events.c:750:9
    #18 0x55a96a562b26 in synth_all tools/perf/tests/mmap-thread-lookup.c:136:9
    #19 0x55a96a5623b1 in mmap_events tools/perf/tests/mmap-thread-lookup.c:174:8
    #20 0x55a96a561fa0 in test__mmap_thread_lookup tools/perf/tests/mmap-thread-lookup.c:230:2
    #21 0x55a96a52c182 in run_test tools/perf/tests/builtin-test.c:378:9
    #22 0x55a96a52afc1 in test_and_print tools/perf/tests/builtin-test.c:408:9
    #23 0x55a96a52966e in __cmd_test tools/perf/tests/builtin-test.c:603:4
    #24 0x55a96a52855d in cmd_test tools/perf/tests/builtin-test.c:747:9
    #25 0x55a96a2844d4 in run_builtin tools/perf/perf.c:312:11
    #26 0x55a96a282bd0 in handle_internal_command tools/perf/perf.c:364:8
    #27 0x55a96a284097 in run_argv tools/perf/perf.c:408:2
    #28 0x55a96a282223 in main tools/perf/perf.c:538:3

  Uninitialized value was stored to memory at
    #1 0x55a96a6a18f7 in dso__new_id tools/perf/util/dso.c:1230:14
    #2 0x55a96a6a78ee in __dsos__addnew_id tools/perf/util/dsos.c:233:20
    #3 0x55a96a6a7bcc in __dsos__findnew_id tools/perf/util/dsos.c:252:21
    #4 0x55a96a6a7a57 in dsos__findnew_id tools/perf/util/dsos.c:259:17
    #5 0x55a96a7776ae in machine__findnew_dso_id tools/perf/util/machine.c:2709:9
    #6 0x55a96a77dfcf in map__new tools/perf/util/map.c:193:10
    #7 0x55a96a77240a in machine__process_mmap2_event tools/perf/util/machine.c:1670:8
    #8 0x55a96a7741a3 in machine__process_event tools/perf/util/machine.c:1882:9
    #9 0x55a96a6aee39 in perf_event__process tools/perf/util/event.c:454:9
    #10 0x55a96a87d633 in perf_tool__process_synth_event tools/perf/util/synthetic-events.c:63:9
    #11 0x55a96a87f131 in perf_event__synthesize_mmap_events tools/perf/util/synthetic-events.c:403:7
    #12 0x55a96a8815d6 in __event__synthesize_thread tools/perf/util/synthetic-events.c:548:9
    #13 0x55a96a882bff in __perf_event__synthesize_threads tools/perf/util/synthetic-events.c:681:3
    #14 0x55a96a881ec2 in perf_event__synthesize_threads tools/perf/util/synthetic-events.c:750:9
    #15 0x55a96a562b26 in synth_all tools/perf/tests/mmap-thread-lookup.c:136:9
    #16 0x55a96a5623b1 in mmap_events tools/perf/tests/mmap-thread-lookup.c:174:8
    #17 0x55a96a561fa0 in test__mmap_thread_lookup tools/perf/tests/mmap-thread-lookup.c:230:2
    #18 0x55a96a52c182 in run_test tools/perf/tests/builtin-test.c:378:9
    #19 0x55a96a52afc1 in test_and_print tools/perf/tests/builtin-test.c:408:9

  Uninitialized value was stored to memory at
    #0 0x55a96a7725af in machine__process_mmap2_event tools/perf/util/machine.c:1646:25
    #1 0x55a96a7741a3 in machine__process_event tools/perf/util/machine.c:1882:9
    #2 0x55a96a6aee39 in perf_event__process tools/perf/util/event.c:454:9
    #3 0x55a96a87d633 in perf_tool__process_synth_event tools/perf/util/synthetic-events.c:63:9
    #4 0x55a96a87f131 in perf_event__synthesize_mmap_events tools/perf/util/synthetic-events.c:403:7
    #5 0x55a96a8815d6 in __event__synthesize_thread tools/perf/util/synthetic-events.c:548:9
    #6 0x55a96a882bff in __perf_event__synthesize_threads tools/perf/util/synthetic-events.c:681:3
    #7 0x55a96a881ec2 in perf_event__synthesize_threads tools/perf/util/synthetic-events.c:750:9
    #8 0x55a96a562b26 in synth_all tools/perf/tests/mmap-thread-lookup.c:136:9
    #9 0x55a96a5623b1 in mmap_events tools/perf/tests/mmap-thread-lookup.c:174:8
    #10 0x55a96a561fa0 in test__mmap_thread_lookup tools/perf/tests/mmap-thread-lookup.c:230:2
    #11 0x55a96a52c182 in run_test tools/perf/tests/builtin-test.c:378:9
    #12 0x55a96a52afc1 in test_and_print tools/perf/tests/builtin-test.c:408:9
    #13 0x55a96a52966e in __cmd_test tools/perf/tests/builtin-test.c:603:4
    #14 0x55a96a52855d in cmd_test tools/perf/tests/builtin-test.c:747:9
    #15 0x55a96a2844d4 in run_builtin tools/perf/perf.c:312:11
    #16 0x55a96a282bd0 in handle_internal_command tools/perf/perf.c:364:8
    #17 0x55a96a284097 in run_argv tools/perf/perf.c:408:2
    #18 0x55a96a282223 in main tools/perf/perf.c:538:3

  Uninitialized value was created by a heap allocation
    #0 0x55a96a22f60d in malloc llvm/llvm-project/compiler-rt/lib/msan/msan_interceptors.cpp:925:3
    #1 0x55a96a882948 in __perf_event__synthesize_threads tools/perf/util/synthetic-events.c:655:15
    #2 0x55a96a881ec2 in perf_event__synthesize_threads tools/perf/util/synthetic-events.c:750:9
    #3 0x55a96a562b26 in synth_all tools/perf/tests/mmap-thread-lookup.c:136:9
    #4 0x55a96a5623b1 in mmap_events tools/perf/tests/mmap-thread-lookup.c:174:8
    #5 0x55a96a561fa0 in test__mmap_thread_lookup tools/perf/tests/mmap-thread-lookup.c:230:2
    #6 0x55a96a52c182 in run_test tools/perf/tests/builtin-test.c:378:9
    #7 0x55a96a52afc1 in test_and_print tools/perf/tests/builtin-test.c:408:9
    #8 0x55a96a52966e in __cmd_test tools/perf/tests/builtin-test.c:603:4
    #9 0x55a96a52855d in cmd_test tools/perf/tests/builtin-test.c:747:9
    #10 0x55a96a2844d4 in run_builtin tools/perf/perf.c:312:11
    #11 0x55a96a282bd0 in handle_internal_command tools/perf/perf.c:364:8
    #12 0x55a96a284097 in run_argv tools/perf/perf.c:408:2
    #13 0x55a96a282223 in main tools/perf/perf.c:538:3

SUMMARY: MemorySanitizer: use-of-uninitialized-value tools/perf/util/dsos.c:23:6 in __dso_id__cmp

Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: clang-built-linux@googlegroups.com
Link: http://lore.kernel.org/lkml/20200313053129.131264-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
nathanchance pushed a commit that referenced this issue Jun 2, 2020
We need to check mddev->del_work before flush workqueu since the purpose
of flush is to ensure the previous md is disappeared. Otherwise the similar
deadlock appeared if LOCKDEP is enabled, it is due to md_open holds the
bdev->bd_mutex before flush workqueue.

kernel: [  154.522645] ======================================================
kernel: [  154.522647] WARNING: possible circular locking dependency detected
kernel: [  154.522650] 5.6.0-rc7-lp151.27-default #25 Tainted: G           O
kernel: [  154.522651] ------------------------------------------------------
kernel: [  154.522653] mdadm/2482 is trying to acquire lock:
kernel: [  154.522655] ffff888078529128 ((wq_completion)md_misc){+.+.}, at: flush_workqueue+0x84/0x4b0
kernel: [  154.522673]
kernel: [  154.522673] but task is already holding lock:
kernel: [  154.522675] ffff88804efa9338 (&bdev->bd_mutex){+.+.}, at: __blkdev_get+0x79/0x590
kernel: [  154.522691]
kernel: [  154.522691] which lock already depends on the new lock.
kernel: [  154.522691]
kernel: [  154.522694]
kernel: [  154.522694] the existing dependency chain (in reverse order) is:
kernel: [  154.522696]
kernel: [  154.522696] -> #4 (&bdev->bd_mutex){+.+.}:
kernel: [  154.522704]        __mutex_lock+0x87/0x950
kernel: [  154.522706]        __blkdev_get+0x79/0x590
kernel: [  154.522708]        blkdev_get+0x65/0x140
kernel: [  154.522709]        blkdev_get_by_dev+0x2f/0x40
kernel: [  154.522716]        lock_rdev+0x3d/0x90 [md_mod]
kernel: [  154.522719]        md_import_device+0xd6/0x1b0 [md_mod]
kernel: [  154.522723]        new_dev_store+0x15e/0x210 [md_mod]
kernel: [  154.522728]        md_attr_store+0x7a/0xc0 [md_mod]
kernel: [  154.522732]        kernfs_fop_write+0x117/0x1b0
kernel: [  154.522735]        vfs_write+0xad/0x1a0
kernel: [  154.522737]        ksys_write+0xa4/0xe0
kernel: [  154.522745]        do_syscall_64+0x64/0x2b0
kernel: [  154.522748]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
kernel: [  154.522749]
kernel: [  154.522749] -> #3 (&mddev->reconfig_mutex){+.+.}:
kernel: [  154.522752]        __mutex_lock+0x87/0x950
kernel: [  154.522756]        new_dev_store+0xc9/0x210 [md_mod]
kernel: [  154.522759]        md_attr_store+0x7a/0xc0 [md_mod]
kernel: [  154.522761]        kernfs_fop_write+0x117/0x1b0
kernel: [  154.522763]        vfs_write+0xad/0x1a0
kernel: [  154.522765]        ksys_write+0xa4/0xe0
kernel: [  154.522767]        do_syscall_64+0x64/0x2b0
kernel: [  154.522769]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
kernel: [  154.522770]
kernel: [  154.522770] -> #2 (kn->count#253){++++}:
kernel: [  154.522775]        __kernfs_remove+0x253/0x2c0
kernel: [  154.522778]        kernfs_remove+0x1f/0x30
kernel: [  154.522780]        kobject_del+0x28/0x60
kernel: [  154.522783]        mddev_delayed_delete+0x24/0x30 [md_mod]
kernel: [  154.522786]        process_one_work+0x2a7/0x5f0
kernel: [  154.522788]        worker_thread+0x2d/0x3d0
kernel: [  154.522793]        kthread+0x117/0x130
kernel: [  154.522795]        ret_from_fork+0x3a/0x50
kernel: [  154.522796]
kernel: [  154.522796] -> #1 ((work_completion)(&mddev->del_work)){+.+.}:
kernel: [  154.522800]        process_one_work+0x27e/0x5f0
kernel: [  154.522802]        worker_thread+0x2d/0x3d0
kernel: [  154.522804]        kthread+0x117/0x130
kernel: [  154.522806]        ret_from_fork+0x3a/0x50
kernel: [  154.522807]
kernel: [  154.522807] -> #0 ((wq_completion)md_misc){+.+.}:
kernel: [  154.522813]        __lock_acquire+0x1392/0x1690
kernel: [  154.522816]        lock_acquire+0xb4/0x1a0
kernel: [  154.522818]        flush_workqueue+0xab/0x4b0
kernel: [  154.522821]        md_open+0xb6/0xc0 [md_mod]
kernel: [  154.522823]        __blkdev_get+0xea/0x590
kernel: [  154.522825]        blkdev_get+0x65/0x140
kernel: [  154.522828]        do_dentry_open+0x1d1/0x380
kernel: [  154.522831]        path_openat+0x567/0xcc0
kernel: [  154.522834]        do_filp_open+0x9b/0x110
kernel: [  154.522836]        do_sys_openat2+0x201/0x2a0
kernel: [  154.522838]        do_sys_open+0x57/0x80
kernel: [  154.522840]        do_syscall_64+0x64/0x2b0
kernel: [  154.522842]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
kernel: [  154.522844]
kernel: [  154.522844] other info that might help us debug this:
kernel: [  154.522844]
kernel: [  154.522846] Chain exists of:
kernel: [  154.522846]   (wq_completion)md_misc --> &mddev->reconfig_mutex --> &bdev->bd_mutex
kernel: [  154.522846]
kernel: [  154.522850]  Possible unsafe locking scenario:
kernel: [  154.522850]
kernel: [  154.522852]        CPU0                    CPU1
kernel: [  154.522853]        ----                    ----
kernel: [  154.522854]   lock(&bdev->bd_mutex);
kernel: [  154.522856]                                lock(&mddev->reconfig_mutex);
kernel: [  154.522858]                                lock(&bdev->bd_mutex);
kernel: [  154.522860]   lock((wq_completion)md_misc);
kernel: [  154.522861]
kernel: [  154.522861]  *** DEADLOCK ***
kernel: [  154.522861]
kernel: [  154.522864] 1 lock held by mdadm/2482:
kernel: [  154.522865]  #0: ffff88804efa9338 (&bdev->bd_mutex){+.+.}, at: __blkdev_get+0x79/0x590
kernel: [  154.522868]
kernel: [  154.522868] stack backtrace:
kernel: [  154.522873] CPU: 1 PID: 2482 Comm: mdadm Tainted: G           O      5.6.0-rc7-lp151.27-default #25
kernel: [  154.522875] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
kernel: [  154.522878] Call Trace:
kernel: [  154.522881]  dump_stack+0x8f/0xcb
kernel: [  154.522884]  check_noncircular+0x194/0x1b0
kernel: [  154.522888]  ? __lock_acquire+0x1392/0x1690
kernel: [  154.522890]  __lock_acquire+0x1392/0x1690
kernel: [  154.522893]  lock_acquire+0xb4/0x1a0
kernel: [  154.522895]  ? flush_workqueue+0x84/0x4b0
kernel: [  154.522898]  flush_workqueue+0xab/0x4b0
kernel: [  154.522900]  ? flush_workqueue+0x84/0x4b0
kernel: [  154.522905]  ? md_open+0xb6/0xc0 [md_mod]
kernel: [  154.522908]  md_open+0xb6/0xc0 [md_mod]
kernel: [  154.522910]  __blkdev_get+0xea/0x590
kernel: [  154.522912]  ? bd_acquire+0xc0/0xc0
kernel: [  154.522914]  blkdev_get+0x65/0x140
kernel: [  154.522916]  ? bd_acquire+0xc0/0xc0
kernel: [  154.522918]  do_dentry_open+0x1d1/0x380
kernel: [  154.522921]  path_openat+0x567/0xcc0
kernel: [  154.522923]  ? __lock_acquire+0x380/0x1690
kernel: [  154.522926]  do_filp_open+0x9b/0x110
kernel: [  154.522929]  ? __alloc_fd+0xe5/0x1f0
kernel: [  154.522935]  ? kmem_cache_alloc+0x28c/0x630
kernel: [  154.522939]  ? do_sys_openat2+0x201/0x2a0
kernel: [  154.522941]  do_sys_openat2+0x201/0x2a0
kernel: [  154.522944]  do_sys_open+0x57/0x80
kernel: [  154.522946]  do_syscall_64+0x64/0x2b0
kernel: [  154.522948]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
kernel: [  154.522951] RIP: 0033:0x7f98d279d9ae

And md_alloc also flushed the same workqueue, but the thing is different
here. Because all the paths call md_alloc don't hold bdev->bd_mutex, and
the flush is necessary to avoid race condition, so leave it as it is.

Signed-off-by: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
nathanchance pushed a commit that referenced this issue Aug 2, 2020
I compiled with AddressSanitizer and I had these memory leaks while I
was using the tep_parse_format function:

    Direct leak of 28 byte(s) in 4 object(s) allocated from:
        #0 0x7fb07db49ffe in __interceptor_realloc (/lib/x86_64-linux-gnu/libasan.so.5+0x10dffe)
        #1 0x7fb07a724228 in extend_token /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:985
        #2 0x7fb07a724c21 in __read_token /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:1140
        #3 0x7fb07a724f78 in read_token /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:1206
        #4 0x7fb07a725191 in __read_expect_type /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:1291
        #5 0x7fb07a7251df in read_expect_type /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:1299
        #6 0x7fb07a72e6c8 in process_dynamic_array_len /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:2849
        #7 0x7fb07a7304b8 in process_function /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:3161
        #8 0x7fb07a730900 in process_arg_token /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:3207
        #9 0x7fb07a727c0b in process_arg /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:1786
        #10 0x7fb07a731080 in event_read_print_args /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:3285
        #11 0x7fb07a731722 in event_read_print /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:3369
        #12 0x7fb07a740054 in __tep_parse_format /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:6335
        #13 0x7fb07a74047a in __parse_event /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:6389
        #14 0x7fb07a740536 in tep_parse_format /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:6431
        #15 0x7fb07a785acf in parse_event ../../../src/fs-src/fs.c:251
        #16 0x7fb07a785ccd in parse_systems ../../../src/fs-src/fs.c:284
        #17 0x7fb07a786fb3 in read_metadata ../../../src/fs-src/fs.c:593
        #18 0x7fb07a78760e in ftrace_fs_source_init ../../../src/fs-src/fs.c:727
        #19 0x7fb07d90c19c in add_component_with_init_method_data ../../../../src/lib/graph/graph.c:1048
        #20 0x7fb07d90c87b in add_source_component_with_initialize_method_data ../../../../src/lib/graph/graph.c:1127
        #21 0x7fb07d90c92a in bt_graph_add_source_component ../../../../src/lib/graph/graph.c:1152
        #22 0x55db11aa632e in cmd_run_ctx_create_components_from_config_components ../../../src/cli/babeltrace2.c:2252
        #23 0x55db11aa6fda in cmd_run_ctx_create_components ../../../src/cli/babeltrace2.c:2347
        #24 0x55db11aa780c in cmd_run ../../../src/cli/babeltrace2.c:2461
        #25 0x55db11aa8a7d in main ../../../src/cli/babeltrace2.c:2673
        #26 0x7fb07d5460b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x270b2)

The token variable in the process_dynamic_array_len function is
allocated in the read_expect_type function, but is not freed before
calling the read_token function.

Free the token variable before calling read_token in order to plug the
leak.

Signed-off-by: Philippe Duplessis-Guindon <pduplessis@efficios.com>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Link: https://lore.kernel.org/linux-trace-devel/20200730150236.5392-1-pduplessis@efficios.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
nathanchance pushed a commit that referenced this issue Aug 5, 2020
The following deadlock was captured. The first process is holding 'kernfs_mutex'
and hung by io. The io was staging in 'r1conf.pending_bio_list' of raid1 device,
this pending bio list would be flushed by second process 'md127_raid1', but
it was hung by 'kernfs_mutex'. Using sysfs_notify_dirent_safe() to replace
sysfs_notify() can fix it. There were other sysfs_notify() invoked from io
path, removed all of them.

 PID: 40430  TASK: ffff8ee9c8c65c40  CPU: 29  COMMAND: "probe_file"
  #0 [ffffb87c4df37260] __schedule at ffffffff9a8678ec
  #1 [ffffb87c4df372f8] schedule at ffffffff9a867f06
  #2 [ffffb87c4df37310] io_schedule at ffffffff9a0c73e6
  #3 [ffffb87c4df37328] __dta___xfs_iunpin_wait_3443 at ffffffffc03a4057 [xfs]
  #4 [ffffb87c4df373a0] xfs_iunpin_wait at ffffffffc03a6c79 [xfs]
  #5 [ffffb87c4df373b0] __dta_xfs_reclaim_inode_3357 at ffffffffc039a46c [xfs]
  #6 [ffffb87c4df37400] xfs_reclaim_inodes_ag at ffffffffc039a8b6 [xfs]
  #7 [ffffb87c4df37590] xfs_reclaim_inodes_nr at ffffffffc039bb33 [xfs]
  #8 [ffffb87c4df375b0] xfs_fs_free_cached_objects at ffffffffc03af0e9 [xfs]
  #9 [ffffb87c4df375c0] super_cache_scan at ffffffff9a287ec7
 #10 [ffffb87c4df37618] shrink_slab at ffffffff9a1efd93
 #11 [ffffb87c4df37700] shrink_node at ffffffff9a1f5968
 #12 [ffffb87c4df37788] do_try_to_free_pages at ffffffff9a1f5ea2
 #13 [ffffb87c4df377f0] try_to_free_mem_cgroup_pages at ffffffff9a1f6445
 #14 [ffffb87c4df37880] try_charge at ffffffff9a26cc5f
 #15 [ffffb87c4df37920] memcg_kmem_charge_memcg at ffffffff9a270f6a
 #16 [ffffb87c4df37958] new_slab at ffffffff9a251430
 #17 [ffffb87c4df379c0] ___slab_alloc at ffffffff9a251c85
 #18 [ffffb87c4df37a80] __slab_alloc at ffffffff9a25635d
 #19 [ffffb87c4df37ac0] kmem_cache_alloc at ffffffff9a251f89
 #20 [ffffb87c4df37b00] alloc_inode at ffffffff9a2a2b10
 #21 [ffffb87c4df37b20] iget_locked at ffffffff9a2a4854
 #22 [ffffb87c4df37b60] kernfs_get_inode at ffffffff9a311377
 #23 [ffffb87c4df37b80] kernfs_iop_lookup at ffffffff9a311e2b
 #24 [ffffb87c4df37ba8] lookup_slow at ffffffff9a290118
 #25 [ffffb87c4df37c10] walk_component at ffffffff9a291e83
 #26 [ffffb87c4df37c78] path_lookupat at ffffffff9a293619
 #27 [ffffb87c4df37cd8] filename_lookup at ffffffff9a2953af
 #28 [ffffb87c4df37de8] user_path_at_empty at ffffffff9a295566
 #29 [ffffb87c4df37e10] vfs_statx at ffffffff9a289787
 #30 [ffffb87c4df37e70] SYSC_newlstat at ffffffff9a289d5d
 #31 [ffffb87c4df37f18] sys_newlstat at ffffffff9a28a60e
 #32 [ffffb87c4df37f28] do_syscall_64 at ffffffff9a003949
 #33 [ffffb87c4df37f50] entry_SYSCALL_64_after_hwframe at ffffffff9aa001ad
     RIP: 00007f617a5f2905  RSP: 00007f607334f838  RFLAGS: 00000246
     RAX: ffffffffffffffda  RBX: 00007f6064044b20  RCX: 00007f617a5f2905
     RDX: 00007f6064044b20  RSI: 00007f6064044b20  RDI: 00007f6064005890
     RBP: 00007f6064044aa0   R8: 0000000000000030   R9: 000000000000011c
     R10: 0000000000000013  R11: 0000000000000246  R12: 00007f606417e6d0
     R13: 00007f6064044aa0  R14: 00007f6064044b10  R15: 00000000ffffffff
     ORIG_RAX: 0000000000000006  CS: 0033  SS: 002b

 PID: 927    TASK: ffff8f15ac5dbd80  CPU: 42  COMMAND: "md127_raid1"
  #0 [ffffb87c4df07b28] __schedule at ffffffff9a8678ec
  #1 [ffffb87c4df07bc0] schedule at ffffffff9a867f06
  #2 [ffffb87c4df07bd8] schedule_preempt_disabled at ffffffff9a86825e
  #3 [ffffb87c4df07be8] __mutex_lock at ffffffff9a869bcc
  #4 [ffffb87c4df07ca0] __mutex_lock_slowpath at ffffffff9a86a013
  #5 [ffffb87c4df07cb0] mutex_lock at ffffffff9a86a04f
  #6 [ffffb87c4df07cc8] kernfs_find_and_get_ns at ffffffff9a311d83
  #7 [ffffb87c4df07cf0] sysfs_notify at ffffffff9a314b3a
  #8 [ffffb87c4df07d18] md_update_sb at ffffffff9a688696
  #9 [ffffb87c4df07d98] md_update_sb at ffffffff9a6886d5
 #10 [ffffb87c4df07da8] md_check_recovery at ffffffff9a68ad9c
 #11 [ffffb87c4df07dd0] raid1d at ffffffffc01f0375 [raid1]
 #12 [ffffb87c4df07ea0] md_thread at ffffffff9a680348
 #13 [ffffb87c4df07f08] kthread at ffffffff9a0b8005
 #14 [ffffb87c4df07f50] ret_from_fork at ffffffff9aa00344

Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
nathanchance pushed a commit that referenced this issue Sep 26, 2020
Patch series "mm: fix memory to node bad links in sysfs", v3.

Sometimes, firmware may expose interleaved memory layout like this:

 Early memory node ranges
   node   1: [mem 0x0000000000000000-0x000000011fffffff]
   node   2: [mem 0x0000000120000000-0x000000014fffffff]
   node   1: [mem 0x0000000150000000-0x00000001ffffffff]
   node   0: [mem 0x0000000200000000-0x000000048fffffff]
   node   2: [mem 0x0000000490000000-0x00000007ffffffff]

In that case, we can see memory blocks assigned to multiple nodes in
sysfs:

  $ ls -l /sys/devices/system/memory/memory21
  total 0
  lrwxrwxrwx 1 root root     0 Aug 24 05:27 node1 -> ../../node/node1
  lrwxrwxrwx 1 root root     0 Aug 24 05:27 node2 -> ../../node/node2
  -rw-r--r-- 1 root root 65536 Aug 24 05:27 online
  -r--r--r-- 1 root root 65536 Aug 24 05:27 phys_device
  -r--r--r-- 1 root root 65536 Aug 24 05:27 phys_index
  drwxr-xr-x 2 root root     0 Aug 24 05:27 power
  -r--r--r-- 1 root root 65536 Aug 24 05:27 removable
  -rw-r--r-- 1 root root 65536 Aug 24 05:27 state
  lrwxrwxrwx 1 root root     0 Aug 24 05:25 subsystem -> ../../../../bus/memory
  -rw-r--r-- 1 root root 65536 Aug 24 05:25 uevent
  -r--r--r-- 1 root root 65536 Aug 24 05:27 valid_zones

The same applies in the node's directory with a memory21 link in both
the node1 and node2's directory.

This is wrong but doesn't prevent the system to run.  However when
later, one of these memory blocks is hot-unplugged and then hot-plugged,
the system is detecting an inconsistency in the sysfs layout and a
BUG_ON() is raised:

  kernel BUG at /Users/laurent/src/linux-ppc/mm/memory_hotplug.c:1084!
  LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
  Modules linked in: rpadlpar_io rpaphp pseries_rng rng_core vmx_crypto gf128mul binfmt_misc ip_tables x_tables xfs libcrc32c crc32c_vpmsum autofs4
  CPU: 8 PID: 10256 Comm: drmgr Not tainted 5.9.0-rc1+ #25
  Call Trace:
    add_memory_resource+0x23c/0x340 (unreliable)
    __add_memory+0x5c/0xf0
    dlpar_add_lmb+0x1b4/0x500
    dlpar_memory+0x1f8/0xb80
    handle_dlpar_errorlog+0xc0/0x190
    dlpar_store+0x198/0x4a0
    kobj_attr_store+0x30/0x50
    sysfs_kf_write+0x64/0x90
    kernfs_fop_write+0x1b0/0x290
    vfs_write+0xe8/0x290
    ksys_write+0xdc/0x130
    system_call_exception+0x160/0x270
    system_call_common+0xf0/0x27c

This has been seen on PowerPC LPAR.

The root cause of this issue is that when node's memory is registered,
the range used can overlap another node's range, thus the memory block
is registered to multiple nodes in sysfs.

There are two issues here:

 (a) The sysfs memory and node's layouts are broken due to these
     multiple links

 (b) The link errors in link_mem_sections() should not lead to a system
     panic.

To address (a) register_mem_sect_under_node should not rely on the
system state to detect whether the link operation is triggered by a hot
plug operation or not.  This is addressed by the patches 1 and 2 of this
series.

Issue (b) will be addressed separately.

This patch (of 2):

The memmap_context enum is used to detect whether a memory operation is
due to a hot-add operation or happening at boot time.

Make it general to the hotplug operation and rename it as
meminit_context.

There is no functional change introduced by this patch

Suggested-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J . Wysocki" <rafael@kernel.org>
Cc: Nathan Lynch <nathanl@linux.ibm.com>
Cc: Scott Cheloha <cheloha@linux.ibm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20200915094143.79181-1-ldufour@linux.ibm.com
Link: https://lkml.kernel.org/r/20200915132624.9723-1-ldufour@linux.ibm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
nathanchance pushed a commit that referenced this issue Sep 26, 2020
In register_mem_sect_under_node() the system_state's value is checked to
detect whether the call is made during boot time or during an hot-plug
operation.  Unfortunately, that check against SYSTEM_BOOTING is wrong
because regular memory is registered at SYSTEM_SCHEDULING state.  In
addition, memory hot-plug operation can be triggered at this system
state by the ACPI [1].  So checking against the system state is not
enough.

The consequence is that on system with interleaved node's ranges like this:

 Early memory node ranges
   node   1: [mem 0x0000000000000000-0x000000011fffffff]
   node   2: [mem 0x0000000120000000-0x000000014fffffff]
   node   1: [mem 0x0000000150000000-0x00000001ffffffff]
   node   0: [mem 0x0000000200000000-0x000000048fffffff]
   node   2: [mem 0x0000000490000000-0x00000007ffffffff]

This can be seen on PowerPC LPAR after multiple memory hot-plug and
hot-unplug operations are done.  At the next reboot the node's memory
ranges can be interleaved and since the call to link_mem_sections() is
made in topology_init() while the system is in the SYSTEM_SCHEDULING
state, the node's id is not checked, and the sections registered to
multiple nodes:

  $ ls -l /sys/devices/system/memory/memory21/node*
  total 0
  lrwxrwxrwx 1 root root     0 Aug 24 05:27 node1 -> ../../node/node1
  lrwxrwxrwx 1 root root     0 Aug 24 05:27 node2 -> ../../node/node2

In that case, the system is able to boot but if later one of theses
memory blocks is hot-unplugged and then hot-plugged, the sysfs
inconsistency is detected and this is triggering a BUG_ON():

  kernel BUG at /Users/laurent/src/linux-ppc/mm/memory_hotplug.c:1084!
  Oops: Exception in kernel mode, sig: 5 [#1]
  LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
  Modules linked in: rpadlpar_io rpaphp pseries_rng rng_core vmx_crypto gf128mul binfmt_misc ip_tables x_tables xfs libcrc32c crc32c_vpmsum autofs4
  CPU: 8 PID: 10256 Comm: drmgr Not tainted 5.9.0-rc1+ #25
  Call Trace:
    add_memory_resource+0x23c/0x340 (unreliable)
    __add_memory+0x5c/0xf0
    dlpar_add_lmb+0x1b4/0x500
    dlpar_memory+0x1f8/0xb80
    handle_dlpar_errorlog+0xc0/0x190
    dlpar_store+0x198/0x4a0
    kobj_attr_store+0x30/0x50
    sysfs_kf_write+0x64/0x90
    kernfs_fop_write+0x1b0/0x290
    vfs_write+0xe8/0x290
    ksys_write+0xdc/0x130
    system_call_exception+0x160/0x270
    system_call_common+0xf0/0x27c

This patch addresses the root cause by not relying on the system_state
value to detect whether the call is due to a hot-plug operation.  An
extra parameter is added to link_mem_sections() detailing whether the
operation is due to a hot-plug operation.

[1] According to Oscar Salvador, using this qemu command line, ACPI
memory hotplug operations are raised at SYSTEM_SCHEDULING state:

  $QEMU -enable-kvm -machine pc -smp 4,sockets=4,cores=1,threads=1 -cpu host -monitor pty \
        -m size=$MEM,slots=255,maxmem=4294967296k  \
        -numa node,nodeid=0,cpus=0-3,mem=512 -numa node,nodeid=1,mem=512 \
        -object memory-backend-ram,id=memdimm0,size=134217728 -device pc-dimm,node=0,memdev=memdimm0,id=dimm0,slot=0 \
        -object memory-backend-ram,id=memdimm1,size=134217728 -device pc-dimm,node=0,memdev=memdimm1,id=dimm1,slot=1 \
        -object memory-backend-ram,id=memdimm2,size=134217728 -device pc-dimm,node=0,memdev=memdimm2,id=dimm2,slot=2 \
        -object memory-backend-ram,id=memdimm3,size=134217728 -device pc-dimm,node=0,memdev=memdimm3,id=dimm3,slot=3 \
        -object memory-backend-ram,id=memdimm4,size=134217728 -device pc-dimm,node=1,memdev=memdimm4,id=dimm4,slot=4 \
        -object memory-backend-ram,id=memdimm5,size=134217728 -device pc-dimm,node=1,memdev=memdimm5,id=dimm5,slot=5 \
        -object memory-backend-ram,id=memdimm6,size=134217728 -device pc-dimm,node=1,memdev=memdimm6,id=dimm6,slot=6 \

Fixes: 4fbce63 ("mm/memory_hotplug.c: make register_mem_sect_under_node() a callback of walk_memory_range()")
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Nathan Lynch <nathanl@linux.ibm.com>
Cc: Scott Cheloha <cheloha@linux.ibm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20200915094143.79181-3-ldufour@linux.ibm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
nathanchance pushed a commit that referenced this issue Nov 17, 2020
This fix is for a failure that occurred in the DWARF unwind perf test.

Stack unwinders may probe memory when looking for frames.

Memory sanitizer will poison and track uninitialized memory on the
stack, and on the heap if the value is copied to the heap.

This can lead to false memory sanitizer failures for the use of an
uninitialized value.

Avoid this problem by removing the poison on the copied stack.

The full msan failure with track origins looks like:

==2168==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x559ceb10755b in handle_cfi elfutils/libdwfl/frame_unwind.c:648:8
    #1 0x559ceb105448 in __libdwfl_frame_unwind elfutils/libdwfl/frame_unwind.c:741:4
    #2 0x559ceb0ece90 in dwfl_thread_getframes elfutils/libdwfl/dwfl_frame.c:435:7
    #3 0x559ceb0ec6b7 in get_one_thread_frames_cb elfutils/libdwfl/dwfl_frame.c:379:10
    #4 0x559ceb0ec6b7 in get_one_thread_cb elfutils/libdwfl/dwfl_frame.c:308:17
    #5 0x559ceb0ec6b7 in dwfl_getthreads elfutils/libdwfl/dwfl_frame.c:283:17
    #6 0x559ceb0ec6b7 in getthread elfutils/libdwfl/dwfl_frame.c:354:14
    #7 0x559ceb0ec6b7 in dwfl_getthread_frames elfutils/libdwfl/dwfl_frame.c:388:10
    #8 0x559ceaff6ae6 in unwind__get_entries tools/perf/util/unwind-libdw.c:236:8
    #9 0x559ceabc9dbc in test_dwarf_unwind__thread tools/perf/tests/dwarf-unwind.c:111:8
    #10 0x559ceabca5cf in test_dwarf_unwind__compare tools/perf/tests/dwarf-unwind.c:138:26
    #11 0x7f812a6865b0 in bsearch (libc.so.6+0x4e5b0)
    #12 0x559ceabca871 in test_dwarf_unwind__krava_3 tools/perf/tests/dwarf-unwind.c:162:2
    #13 0x559ceabca926 in test_dwarf_unwind__krava_2 tools/perf/tests/dwarf-unwind.c:169:9
    #14 0x559ceabca946 in test_dwarf_unwind__krava_1 tools/perf/tests/dwarf-unwind.c:174:9
    #15 0x559ceabcae12 in test__dwarf_unwind tools/perf/tests/dwarf-unwind.c:211:8
    #16 0x559ceabbc4ab in run_test tools/perf/tests/builtin-test.c:418:9
    #17 0x559ceabbc4ab in test_and_print tools/perf/tests/builtin-test.c:448:9
    #18 0x559ceabbac70 in __cmd_test tools/perf/tests/builtin-test.c:669:4
    #19 0x559ceabbac70 in cmd_test tools/perf/tests/builtin-test.c:815:9
    #20 0x559cea960e30 in run_builtin tools/perf/perf.c:313:11
    #21 0x559cea95fbce in handle_internal_command tools/perf/perf.c:365:8
    #22 0x559cea95fbce in run_argv tools/perf/perf.c:409:2
    #23 0x559cea95fbce in main tools/perf/perf.c:539:3

  Uninitialized value was stored to memory at
    #0 0x559ceb106acf in __libdwfl_frame_reg_set elfutils/libdwfl/frame_unwind.c:77:22
    #1 0x559ceb106acf in handle_cfi elfutils/libdwfl/frame_unwind.c:627:13
    #2 0x559ceb105448 in __libdwfl_frame_unwind elfutils/libdwfl/frame_unwind.c:741:4
    #3 0x559ceb0ece90 in dwfl_thread_getframes elfutils/libdwfl/dwfl_frame.c:435:7
    #4 0x559ceb0ec6b7 in get_one_thread_frames_cb elfutils/libdwfl/dwfl_frame.c:379:10
    #5 0x559ceb0ec6b7 in get_one_thread_cb elfutils/libdwfl/dwfl_frame.c:308:17
    #6 0x559ceb0ec6b7 in dwfl_getthreads elfutils/libdwfl/dwfl_frame.c:283:17
    #7 0x559ceb0ec6b7 in getthread elfutils/libdwfl/dwfl_frame.c:354:14
    #8 0x559ceb0ec6b7 in dwfl_getthread_frames elfutils/libdwfl/dwfl_frame.c:388:10
    #9 0x559ceaff6ae6 in unwind__get_entries tools/perf/util/unwind-libdw.c:236:8
    #10 0x559ceabc9dbc in test_dwarf_unwind__thread tools/perf/tests/dwarf-unwind.c:111:8
    #11 0x559ceabca5cf in test_dwarf_unwind__compare tools/perf/tests/dwarf-unwind.c:138:26
    #12 0x7f812a6865b0 in bsearch (libc.so.6+0x4e5b0)
    #13 0x559ceabca871 in test_dwarf_unwind__krava_3 tools/perf/tests/dwarf-unwind.c:162:2
    #14 0x559ceabca926 in test_dwarf_unwind__krava_2 tools/perf/tests/dwarf-unwind.c:169:9
    #15 0x559ceabca946 in test_dwarf_unwind__krava_1 tools/perf/tests/dwarf-unwind.c:174:9
    #16 0x559ceabcae12 in test__dwarf_unwind tools/perf/tests/dwarf-unwind.c:211:8
    #17 0x559ceabbc4ab in run_test tools/perf/tests/builtin-test.c:418:9
    #18 0x559ceabbc4ab in test_and_print tools/perf/tests/builtin-test.c:448:9
    #19 0x559ceabbac70 in __cmd_test tools/perf/tests/builtin-test.c:669:4
    #20 0x559ceabbac70 in cmd_test tools/perf/tests/builtin-test.c:815:9
    #21 0x559cea960e30 in run_builtin tools/perf/perf.c:313:11
    #22 0x559cea95fbce in handle_internal_command tools/perf/perf.c:365:8
    #23 0x559cea95fbce in run_argv tools/perf/perf.c:409:2
    #24 0x559cea95fbce in main tools/perf/perf.c:539:3

  Uninitialized value was stored to memory at
    #0 0x559ceb106a54 in handle_cfi elfutils/libdwfl/frame_unwind.c:613:9
    #1 0x559ceb105448 in __libdwfl_frame_unwind elfutils/libdwfl/frame_unwind.c:741:4
    #2 0x559ceb0ece90 in dwfl_thread_getframes elfutils/libdwfl/dwfl_frame.c:435:7
    #3 0x559ceb0ec6b7 in get_one_thread_frames_cb elfutils/libdwfl/dwfl_frame.c:379:10
    #4 0x559ceb0ec6b7 in get_one_thread_cb elfutils/libdwfl/dwfl_frame.c:308:17
    #5 0x559ceb0ec6b7 in dwfl_getthreads elfutils/libdwfl/dwfl_frame.c:283:17
    #6 0x559ceb0ec6b7 in getthread elfutils/libdwfl/dwfl_frame.c:354:14
    #7 0x559ceb0ec6b7 in dwfl_getthread_frames elfutils/libdwfl/dwfl_frame.c:388:10
    #8 0x559ceaff6ae6 in unwind__get_entries tools/perf/util/unwind-libdw.c:236:8
    #9 0x559ceabc9dbc in test_dwarf_unwind__thread tools/perf/tests/dwarf-unwind.c:111:8
    #10 0x559ceabca5cf in test_dwarf_unwind__compare tools/perf/tests/dwarf-unwind.c:138:26
    #11 0x7f812a6865b0 in bsearch (libc.so.6+0x4e5b0)
    #12 0x559ceabca871 in test_dwarf_unwind__krava_3 tools/perf/tests/dwarf-unwind.c:162:2
    #13 0x559ceabca926 in test_dwarf_unwind__krava_2 tools/perf/tests/dwarf-unwind.c:169:9
    #14 0x559ceabca946 in test_dwarf_unwind__krava_1 tools/perf/tests/dwarf-unwind.c:174:9
    #15 0x559ceabcae12 in test__dwarf_unwind tools/perf/tests/dwarf-unwind.c:211:8
    #16 0x559ceabbc4ab in run_test tools/perf/tests/builtin-test.c:418:9
    #17 0x559ceabbc4ab in test_and_print tools/perf/tests/builtin-test.c:448:9
    #18 0x559ceabbac70 in __cmd_test tools/perf/tests/builtin-test.c:669:4
    #19 0x559ceabbac70 in cmd_test tools/perf/tests/builtin-test.c:815:9
    #20 0x559cea960e30 in run_builtin tools/perf/perf.c:313:11
    #21 0x559cea95fbce in handle_internal_command tools/perf/perf.c:365:8
    #22 0x559cea95fbce in run_argv tools/perf/perf.c:409:2
    #23 0x559cea95fbce in main tools/perf/perf.c:539:3

  Uninitialized value was stored to memory at
    #0 0x559ceaff8800 in memory_read tools/perf/util/unwind-libdw.c:156:10
    #1 0x559ceb10f053 in expr_eval elfutils/libdwfl/frame_unwind.c:501:13
    #2 0x559ceb1060cc in handle_cfi elfutils/libdwfl/frame_unwind.c:603:18
    #3 0x559ceb105448 in __libdwfl_frame_unwind elfutils/libdwfl/frame_unwind.c:741:4
    #4 0x559ceb0ece90 in dwfl_thread_getframes elfutils/libdwfl/dwfl_frame.c:435:7
    #5 0x559ceb0ec6b7 in get_one_thread_frames_cb elfutils/libdwfl/dwfl_frame.c:379:10
    #6 0x559ceb0ec6b7 in get_one_thread_cb elfutils/libdwfl/dwfl_frame.c:308:17
    #7 0x559ceb0ec6b7 in dwfl_getthreads elfutils/libdwfl/dwfl_frame.c:283:17
    #8 0x559ceb0ec6b7 in getthread elfutils/libdwfl/dwfl_frame.c:354:14
    #9 0x559ceb0ec6b7 in dwfl_getthread_frames elfutils/libdwfl/dwfl_frame.c:388:10
    #10 0x559ceaff6ae6 in unwind__get_entries tools/perf/util/unwind-libdw.c:236:8
    #11 0x559ceabc9dbc in test_dwarf_unwind__thread tools/perf/tests/dwarf-unwind.c:111:8
    #12 0x559ceabca5cf in test_dwarf_unwind__compare tools/perf/tests/dwarf-unwind.c:138:26
    #13 0x7f812a6865b0 in bsearch (libc.so.6+0x4e5b0)
    #14 0x559ceabca871 in test_dwarf_unwind__krava_3 tools/perf/tests/dwarf-unwind.c:162:2
    #15 0x559ceabca926 in test_dwarf_unwind__krava_2 tools/perf/tests/dwarf-unwind.c:169:9
    #16 0x559ceabca946 in test_dwarf_unwind__krava_1 tools/perf/tests/dwarf-unwind.c:174:9
    #17 0x559ceabcae12 in test__dwarf_unwind tools/perf/tests/dwarf-unwind.c:211:8
    #18 0x559ceabbc4ab in run_test tools/perf/tests/builtin-test.c:418:9
    #19 0x559ceabbc4ab in test_and_print tools/perf/tests/builtin-test.c:448:9
    #20 0x559ceabbac70 in __cmd_test tools/perf/tests/builtin-test.c:669:4
    #21 0x559ceabbac70 in cmd_test tools/perf/tests/builtin-test.c:815:9
    #22 0x559cea960e30 in run_builtin tools/perf/perf.c:313:11
    #23 0x559cea95fbce in handle_internal_command tools/perf/perf.c:365:8
    #24 0x559cea95fbce in run_argv tools/perf/perf.c:409:2
    #25 0x559cea95fbce in main tools/perf/perf.c:539:3

  Uninitialized value was stored to memory at
    #0 0x559cea9027d9 in __msan_memcpy llvm/llvm-project/compiler-rt/lib/msan/msan_interceptors.cpp:1558:3
    #1 0x559cea9d2185 in sample_ustack tools/perf/arch/x86/tests/dwarf-unwind.c:41:2
    #2 0x559cea9d202c in test__arch_unwind_sample tools/perf/arch/x86/tests/dwarf-unwind.c:72:9
    #3 0x559ceabc9cbd in test_dwarf_unwind__thread tools/perf/tests/dwarf-unwind.c:106:6
    #4 0x559ceabca5cf in test_dwarf_unwind__compare tools/perf/tests/dwarf-unwind.c:138:26
    #5 0x7f812a6865b0 in bsearch (libc.so.6+0x4e5b0)
    #6 0x559ceabca871 in test_dwarf_unwind__krava_3 tools/perf/tests/dwarf-unwind.c:162:2
    #7 0x559ceabca926 in test_dwarf_unwind__krava_2 tools/perf/tests/dwarf-unwind.c:169:9
    #8 0x559ceabca946 in test_dwarf_unwind__krava_1 tools/perf/tests/dwarf-unwind.c:174:9
    #9 0x559ceabcae12 in test__dwarf_unwind tools/perf/tests/dwarf-unwind.c:211:8
    #10 0x559ceabbc4ab in run_test tools/perf/tests/builtin-test.c:418:9
    #11 0x559ceabbc4ab in test_and_print tools/perf/tests/builtin-test.c:448:9
    #12 0x559ceabbac70 in __cmd_test tools/perf/tests/builtin-test.c:669:4
    #13 0x559ceabbac70 in cmd_test tools/perf/tests/builtin-test.c:815:9
    #14 0x559cea960e30 in run_builtin tools/perf/perf.c:313:11
    #15 0x559cea95fbce in handle_internal_command tools/perf/perf.c:365:8
    #16 0x559cea95fbce in run_argv tools/perf/perf.c:409:2
    #17 0x559cea95fbce in main tools/perf/perf.c:539:3

  Uninitialized value was created by an allocation of 'bf' in the stack frame of function 'perf_event__synthesize_mmap_events'
    #0 0x559ceafc5f60 in perf_event__synthesize_mmap_events tools/perf/util/synthetic-events.c:445

SUMMARY: MemorySanitizer: use-of-uninitialized-value elfutils/libdwfl/frame_unwind.c:648:8 in handle_cfi
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: clang-built-linux@googlegroups.com
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sandeep Dasgupta <sdasgup@google.com>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20201113182053.754625-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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[ARCH] arm64 This bug impacts ARCH=arm64 [BUG] linux A bug that should be fixed in the mainline kernel. [BUG] llvm A bug that should be fixed in upstream LLVM [FIXED][LINUX] 4.20 This bug was fixed in Linux 4.20 [FIXED][LLVM] 8 This bug was fixed in LLVM 8.0
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