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-m linker option has higher priority than OUTPUT_FORMAT directive #30

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tpimh opened this issue Sep 6, 2018 · 13 comments
Closed

-m linker option has higher priority than OUTPUT_FORMAT directive #30

tpimh opened this issue Sep 6, 2018 · 13 comments
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@vo4
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[ARCH] x86_64 This bug impacts ARCH=x86_64 [BUG] linux A bug that should be fixed in the mainline kernel. [FIXED][LINUX] 5.1 This bug was fixed in Linux 5.1 [TOOL] lld The issue is relevant to LLD linker

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@tpimh
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tpimh commented Sep 6, 2018

Linux kernel uses OUTPUT_FORMAT in it's linker scripts. Most of the time -m option is passed to the linker with correct architecture, but sometimes (at least for x86_64) the -m option contradicts OUTPUT_FORMAT directive (which should have higher priority). My fix is crude: just add correct -m after incorrect one (it overrides it), so the linker invocation looks like this: ld -m elf_x86_64 -z max-page-size=0x200000 -m elf_i386 --emit-relocs -T realmode.lds header.o trampoline_64.o stack.o reboot.o -o realmode.elf (it will also work with GNU ld, because it supports OUTPUT_FORMAT and just ignores -m options if this directive is in the linker script). Ideal solution would be adding OUTPUT_FORMAT support to LLD.

diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile
index 9b5adae..e2839b5 100644
--- a/arch/x86/boot/Makefile
+++ b/arch/x86/boot/Makefile
@@ -100,7 +100,7 @@ $(obj)/zoffset.h: $(obj)/compressed/vmlinux FORCE
 AFLAGS_header.o += -I$(objtree)/$(obj)
 $(obj)/header.o: $(obj)/zoffset.h

-LDFLAGS_setup.elf	:= -T
+LDFLAGS_setup.elf	:= -m elf_i386 -T
 $(obj)/setup.elf: $(src)/setup.ld $(SETUP_OBJS) FORCE
 	$(call if_changed,ld)

diff --git a/arch/x86/realmode/rm/Makefile b/arch/x86/realmode/rm/Makefile
index 4463fa7..96cb20d 100644
--- a/arch/x86/realmode/rm/Makefile
+++ b/arch/x86/realmode/rm/Makefile
@@ -47,7 +47,7 @@ $(obj)/pasyms.h: $(REALMODE_OBJS) FORCE
 targets += realmode.lds
 $(obj)/realmode.lds: $(obj)/pasyms.h

-LDFLAGS_realmode.elf := --emit-relocs -T
+LDFLAGS_realmode.elf := -m elf_i386 --emit-relocs -T
 CPPFLAGS_realmode.lds += -P -C -I$(objtree)/$(obj)

 targets += realmode.elf
@tpimh tpimh added [BUG] llvm A bug that should be fixed in upstream LLVM [TOOL] lld The issue is relevant to LLD linker labels Sep 6, 2018
@nickdesaulniers nickdesaulniers added the low priority This bug is not critical and not a priority label Sep 23, 2018
@nickdesaulniers nickdesaulniers added the [ARCH] x86_64 This bug impacts ARCH=x86_64 label Oct 15, 2018
@nickdesaulniers
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Just for more info, this is what the failure looks like for realmode:

  LD      arch/x86/realmode/rm/realmode.elf
ld.lld: error: arch/x86/realmode/rm/header.o is incompatible with elf_x86_64
ld.lld: error: arch/x86/realmode/rm/trampoline_64.o is incompatible with elf_x86_64
ld.lld: error: arch/x86/realmode/rm/stack.o is incompatible with elf_x86_64
ld.lld: error: arch/x86/realmode/rm/reboot.o is incompatible with elf_x86_64
ld.lld: error: arch/x86/realmode/rm/wakeup_asm.o is incompatible with elf_x86_64
ld.lld: error: arch/x86/realmode/rm/wakemain.o is incompatible with elf_x86_64
ld.lld: error: arch/x86/realmode/rm/video-mode.o is incompatible with elf_x86_64
ld.lld: error: arch/x86/realmode/rm/copy.o is incompatible with elf_x86_64
ld.lld: error: arch/x86/realmode/rm/bioscall.o is incompatible with elf_x86_64
ld.lld: error: arch/x86/realmode/rm/regs.o is incompatible with elf_x86_64
ld.lld: error: arch/x86/realmode/rm/video-vga.o is incompatible with elf_x86_64
ld.lld: error: arch/x86/realmode/rm/video-vesa.o is incompatible with elf_x86_64
ld.lld: error: arch/x86/realmode/rm/video-bios.o is incompatible with elf_x86_64
arch/x86/realmode/rm/Makefile:55: recipe for target 'arch/x86/realmode/rm/realmode.elf' failed

@nickdesaulniers
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nickdesaulniers commented Oct 15, 2018 •
edited by nathanchance
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LLVM bug: https://llvm.org/pr39290

@tpimh
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tpimh commented Oct 15, 2018 •
edited by nathanchance
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Possibly again a duplicate of my bug report: https://llvm.org/pr37432

@tpimh tpimh mentioned this issue Nov 6, 2018
Closed
nathanchance pushed a commit that referenced this issue Nov 9, 2018
s390/kasan: increase instrumented stack size to 64k
9fed920 
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 mentioned this issue Nov 15, 2018
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@tpimh
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tpimh commented Nov 15, 2018 •
edited by nathanchance
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With llvm/llvm-project@ea8cd00 and llvm/llvm-project@4ec5d67 OUTPUT_FORMAT directive is now supported, realmode.elf and setup.elf were linked successfully without adding "-m elf_i386" to LDFLAGS.

@tpimh tpimh closed this as completed Nov 15, 2018
@tpimh tpimh removed the low priority This bug is not critical and not a priority label Nov 15, 2018
@tpimh
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tpimh commented Nov 15, 2018

Turns out -m option has higher priority than OUTPUT_FORMAT directive, thus OUTPUT_FORMAT is parsed correctly and then overridden. Still applying the same patch to build it. Sorry for closing the issue prematurely, reopening.

@tpimh tpimh reopened this Nov 15, 2018
@tpimh tpimh added the low priority This bug is not critical and not a priority label Nov 15, 2018
@tpimh tpimh changed the title LLD doesn't support OUTPUT_FORMAT directive -m linker option has higher priority than OUTPUT_FORMAT directive Nov 15, 2018
@nickdesaulniers nickdesaulniers removed low priority This bug is not critical and not a priority labels Dec 5, 2018
@nickdesaulniers
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@gwelymernans is also looking into this with: https://reviews.llvm.org/D55311. Still discussing this internally with LLD devs.

@tpimh
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tpimh commented Dec 7, 2018

It was reported to kernel bugzilla by George Rimar: https://bugzilla.kernel.org/show_bug.cgi?id=194091

@nickdesaulniers
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Grimar filed: https://bugzilla.kernel.org/show_bug.cgi?id=194091 with the same patch as suggested by @tpimh . I will try to upstream that patch.

@nickdesaulniers nickdesaulniers added [BUG] linux A bug that should be fixed in the mainline kernel. [PATCH] Exists There is a patch that fixes this issue and removed [BUG] llvm A bug that should be fixed in upstream LLVM labels Dec 7, 2018
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@vo4 volunteered to help

@nickdesaulniers nickdesaulniers removed their assignment Dec 7, 2018
@nickdesaulniers
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@vo4 and I spoke more in person about this.

The kernel is adding -m elf_x86_64 to the linker command line parameters, but then relying on binutils tie-breaking-behavior by specifying a different architecture via linker script. So it's ambiguous which arch the kernel is trying to link for, and the kernel gets lucky/relies on the way ld.bfd happens to resolve this ambiguity without warning. An alternative fix may be to just filter out/remove the -m elf_x86_64 for this target's linker flags.

@vo4 sent the patch upstream, but I can't seem to find a link.

@nickdesaulniers nickdesaulniers added [PATCH] Submitted A patch has been submitted for review and removed [PATCH] Exists There is a patch that fixes this issue labels Dec 11, 2018
@tpimh
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tpimh commented Dec 12, 2018 •
edited by nathanchance
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https://lore.kernel.org/r/CANA+-vBcxF7P1C+zddnqshKwMGuCSb97JC-=3==TwFeEGZP05w@mail.gmail.com/

nathanchance pushed a commit that referenced this issue Dec 28, 2018
@kdave
btrfs: skip file_extent generation check for free_space_inode in run_…
27a7ff5 
…delalloc_nocow

The test case btrfs/001 with inode_cache mount option will encounter the
following warning:

  WARNING: CPU: 1 PID: 23700 at fs/btrfs/inode.c:956 cow_file_range.isra.19+0x32b/0x430 [btrfs]
  CPU: 1 PID: 23700 Comm: btrfs Kdump: loaded Tainted: G        W  O      4.20.0-rc4-custom+ #30
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
  RIP: 0010:cow_file_range.isra.19+0x32b/0x430 [btrfs]
  Call Trace:
   ? free_extent_buffer+0x46/0x90 [btrfs]
   run_delalloc_nocow+0x455/0x900 [btrfs]
   btrfs_run_delalloc_range+0x1a7/0x360 [btrfs]
   writepage_delalloc+0xf9/0x150 [btrfs]
   __extent_writepage+0x125/0x3e0 [btrfs]
   extent_write_cache_pages+0x1b6/0x3e0 [btrfs]
   ? __wake_up_common_lock+0x63/0xc0
   extent_writepages+0x50/0x80 [btrfs]
   do_writepages+0x41/0xd0
   ? __filemap_fdatawrite_range+0x9e/0xf0
   __filemap_fdatawrite_range+0xbe/0xf0
   btrfs_fdatawrite_range+0x1b/0x50 [btrfs]
   __btrfs_write_out_cache+0x42c/0x480 [btrfs]
   btrfs_write_out_ino_cache+0x84/0xd0 [btrfs]
   btrfs_save_ino_cache+0x551/0x660 [btrfs]
   commit_fs_roots+0xc5/0x190 [btrfs]
   btrfs_commit_transaction+0x2bf/0x8d0 [btrfs]
   btrfs_mksubvol+0x48d/0x4d0 [btrfs]
   btrfs_ioctl_snap_create_transid+0x170/0x180 [btrfs]
   btrfs_ioctl_snap_create_v2+0x124/0x180 [btrfs]
   btrfs_ioctl+0x123f/0x3030 [btrfs]

The file extent generation of the free space inode is equal to the last
snapshot of the file root, so the inode will be passed to cow_file_rage.
But the inode was created and its extents were preallocated in
btrfs_save_ino_cache, there are no cow copies on disk.

The preallocated extent is not yet in the extent tree, and
btrfs_cross_ref_exist will ignore the -ENOENT returned by
check_committed_ref, so we can directly write the inode to the disk.

Fixes: 78d4295 ("btrfs: lift some btrfs_cross_ref_exist checks in nocow path")
CC: stable@vger.kernel.org # 4.18+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
@nathanchance
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Patch accepted: https://git.kernel.org/tip/927185c124d62a9a4d35878d7f6d432a166b74e3

@nathanchance nathanchance added [PATCH] Accepted A submitted patch has been accepted upstream and removed [PATCH] Submitted A patch has been submitted for review labels Jan 13, 2019
nathanchance pushed a commit that referenced this issue Mar 6, 2019
@mhiramat
x86/kprobes: Prohibit probing on IRQ handlers directly
0eae81d 
Prohibit probing on IRQ handlers in irqentry_text because
if it interrupts user mode, at that point we haven't changed
to kernel space yet and which eventually leads a double fault.
E.g.

 # echo p apic_timer_interrupt > kprobe_events
 # echo 1 > events/kprobes/enable
 PANIC: double fault, error_code: 0x0
 CPU: 1 PID: 814 Comm: less Not tainted 4.20.0-rc3+ #30
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
 RIP: 0010:error_entry+0x12/0xf0
 [snip]
 Call Trace:
  <ENTRY_TRAMPOLINE>
  ? native_iret+0x7/0x7
  ? async_page_fault+0x8/0x30
  ? trace_hardirqs_on_thunk+0x1c/0x1c
  ? error_entry+0x7c/0xf0
  ? async_page_fault+0x8/0x30
  ? native_iret+0x7/0x7
  ? int3+0xa/0x20
  ? trace_hardirqs_on_thunk+0x1c/0x1c
  ? error_entry+0x7c/0xf0
  ? int3+0xa/0x20
  ? apic_timer_interrupt+0x1/0x20
  </ENTRY_TRAMPOLINE>
 Kernel panic - not syncing: Machine halted.
 Kernel Offset: disabled
 ---[ end Kernel panic - not syncing: Machine halted. ]---

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrea Righi <righi.andrea@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/154998796400.31052.8406236614820687840.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merged into mainline: https://git.kernel.org/torvalds/c/927185c124d62a9a4d35878d7f6d432a166b74e3

@nathanchance nathanchance added [FIXED][LINUX] 5.1 This bug was fixed in Linux 5.1 and removed [PATCH] Accepted A submitted patch has been accepted upstream labels Mar 8, 2019
nathanchance pushed a commit that referenced this issue Mar 22, 2019
@shcgit @storulf
mmc: mxcmmc: "Revert mmc: mxcmmc: handle highmem pages"
2b77158 
This reverts commit b189e75.

Unable to handle kernel paging request at virtual address c8358000
pgd = efa405c3
[c8358000] *pgd=00000000
Internal error: Oops: 805 [#1] PREEMPT ARM
CPU: 0 PID: 711 Comm: kworker/0:2 Not tainted 4.20.0+ #30
Hardware name: Freescale i.MX27 (Device Tree Support)
Workqueue: events mxcmci_datawork
PC is at mxcmci_datawork+0xbc/0x2ac
LR is at mxcmci_datawork+0xac/0x2ac
pc : [<c04e33c8>]    lr : [<c04e33b8>]    psr: 60000013
sp : c6c93f08  ip : 24004180  fp : 00000008
r10: c8358000  r9 : c78b3e24  r8 : c6c92000
r7 : 00000000  r6 : c7bb8680  r5 : c7bb86d4  r4 : c78b3de0
r3 : 00002502  r2 : c090b2e0  r1 : 00000880  r0 : 00000000
Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
Control: 0005317f  Table: a68a8000  DAC: 00000055
Process kworker/0:2 (pid: 711, stack limit = 0x389543bc)
Stack: (0xc6c93f08 to 0xc6c94000)
3f00:                   c7bb86d4 00000000 00000000 c6cbfde0 c7bb86d4 c7ee4200
3f20: 00000000 c0907ea8 00000000 c7bb86d8 c0907ea8 c012077c c6cbfde0 c7bb86d4
3f40: c6cbfde0 c6c92000 c6cbfdf4 c09280ba c0907ea8 c090b2e0 c0907ebc c0120c18
3f60: c6cbfde0 00000000 00000000 c6cbb580 c7ba7c40 c7837edc c6cbb598 00000000
3f80: c6cbfde0 c01208f8 00000000 c01254fc c7ba7c40 c0125400 00000000 00000000
3fa0: 00000000 00000000 00000000 c01010d0 00000000 00000000 00000000 00000000
3fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
3fe0: 00000000 00000000 00000000 00000000 00000013 00000000 00000000 00000000
[<c04e33c8>] (mxcmci_datawork) from [<c012077c>] (process_one_work+0x1f0/0x338)
[<c012077c>] (process_one_work) from [<c0120c18>] (worker_thread+0x320/0x474)
[<c0120c18>] (worker_thread) from [<c01254fc>] (kthread+0xfc/0x118)
[<c01254fc>] (kthread) from [<c01010d0>] (ret_from_fork+0x14/0x24)
Exception stack(0xc6c93fb0 to 0xc6c93ff8)
3fa0:                                     00000000 00000000 00000000 00000000
3fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
3fe0: 00000000 00000000 00000000 00000000 00000013 00000000
Code: e3500000 1a000059 e5153050 e5933038 (e48a3004)
---[ end trace 54ca629b75f0e737 ]---
note: kworker/0:2[711] exited with preempt_count 1

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Fixes: b189e75 ("mmc: mxcmmc: handle highmem pages")
Cc: stable@vger.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
nathanchance pushed a commit that referenced this issue May 8, 2019
@mchehab
media: au0828: Fix NULL pointer dereference in au0828_analog_stream_e…
898bc40 
…nable()

Fix au0828_analog_stream_enable() to check if device is in the right
state first. When unbind happens while bind is in progress, usbdev
pointer could be invalid in au0828_analog_stream_enable() and a call
to usb_ifnum_to_if() will result in the null pointer dereference.

This problem is found with the new media_dev_allocator.sh test.

kernel: [  590.359623] BUG: unable to handle kernel NULL pointer dereference at 00000000000004e8
kernel: [  590.359627] #PF error: [normal kernel read fault]
kernel: [  590.359629] PGD 0 P4D 0
kernel: [  590.359632] Oops: 0000 [#1] SMP PTI
kernel: [  590.359634] CPU: 3 PID: 1458 Comm: v4l_id Not tainted 5.1.0-rc2+ #30
kernel: [  590.359636] Hardware name: Dell Inc. OptiPlex 7 90/0HY9JP, BIOS A18 09/24/2013
kernel: [  590.359641] RIP: 0010:usb_ifnum_to_if+0x6/0x60
kernel: [  590.359643] Code: 5d 41 5e 41 5f 5d c3 48 83 c4
 10 b8 fa ff ff ff 5b 41 5c 41 5d 41 5e 41 5f 5d c3 b8 fa ff ff ff c3 0f 1f 00 6
6 66 66 66 90 55 <48> 8b 97 e8 04 00 00 48 89 e5 48 85 d2 74 41 0f b6 4a 04 84 c
9 74
kernel: [  590.359645] RSP: 0018:ffffad3cc3c1fc00 EFLAGS: 00010246
kernel: [  590.359646] RAX: 0000000000000000 RBX: ffff8ded b1f3c000 RCX: 1f377e4500000000
kernel: [  590.359648] RDX: ffff8dedfa3a6b50 RSI: 00000000 00000000 RDI: 0000000000000000
kernel: [  590.359649] RBP: ffffad3cc3c1fc28 R08: 00000000 8574acc2 R09: ffff8dedfa3a6b50
kernel: [  590.359650] R10: 0000000000000001 R11: 00000000 00000000 R12: 0000000000000000
kernel: [  590.359652] R13: ffff8dedb1f3f0f0 R14: ffffffff adcf7ec0 R15: 0000000000000000
kernel: [  590.359654] FS:  00007f7917198540(0000) GS:ffff 8dee258c0000(0000) knlGS:0000000000000000
kernel: [  590.359655] CS:  0010 DS: 0000 ES: 0000 CR0: 00 00000080050033
kernel: [  590.359657] CR2: 00000000000004e8 CR3: 00000001 a388e002 CR4: 00000000000606e0
kernel: [  590.359658] Call Trace:
kernel: [  590.359664]  ? au0828_analog_stream_enable+0x2c/0x180
kernel: [  590.359666]  au0828_v4l2_open+0xa4/0x110
kernel: [  590.359670]  v4l2_open+0x8b/0x120
kernel: [  590.359674]  chrdev_open+0xa6/0x1c0
kernel: [  590.359676]  ? cdev_put.part.3+0x20/0x20
kernel: [  590.359678]  do_dentry_open+0x1f6/0x360
kernel: [  590.359681]  vfs_open+0x2f/0x40
kernel: [  590.359684]  path_openat+0x299/0xc20
kernel: [  590.359688]  do_filp_open+0x9b/0x110
kernel: [  590.359695]  ? _raw_spin_unlock+0x27/0x40
kernel: [  590.359697]  ? __alloc_fd+0xb2/0x160
kernel: [  590.359700]  do_sys_open+0x1ba/0x260
kernel: [  590.359702]  ? do_sys_open+0x1ba/0x260
kernel: [  590.359712]  __x64_sys_openat+0x20/0x30
kernel: [  590.359715]  do_syscall_64+0x5a/0x120
kernel: [  590.359718]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

Signed-off-by: Shuah Khan <shuah@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
nathanchance pushed a commit that referenced this issue May 31, 2019
@ummakynes
ipvs: Fix use-after-free in ip_vs_in
719c7d5 
BUG: KASAN: use-after-free in ip_vs_in.part.29+0xe8/0xd20 [ip_vs]
Read of size 4 at addr ffff8881e9b26e2c by task sshd/5603

CPU: 0 PID: 5603 Comm: sshd Not tainted 4.19.39+ #30
Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
Call Trace:
 dump_stack+0x71/0xab
 print_address_description+0x6a/0x270
 kasan_report+0x179/0x2c0
 ip_vs_in.part.29+0xe8/0xd20 [ip_vs]
 ip_vs_in+0xd8/0x170 [ip_vs]
 nf_hook_slow+0x5f/0xe0
 __ip_local_out+0x1d5/0x250
 ip_local_out+0x19/0x60
 __tcp_transmit_skb+0xba1/0x14f0
 tcp_write_xmit+0x41f/0x1ed0
 ? _copy_from_iter_full+0xca/0x340
 __tcp_push_pending_frames+0x52/0x140
 tcp_sendmsg_locked+0x787/0x1600
 ? tcp_sendpage+0x60/0x60
 ? inet_sk_set_state+0xb0/0xb0
 tcp_sendmsg+0x27/0x40
 sock_sendmsg+0x6d/0x80
 sock_write_iter+0x121/0x1c0
 ? sock_sendmsg+0x80/0x80
 __vfs_write+0x23e/0x370
 vfs_write+0xe7/0x230
 ksys_write+0xa1/0x120
 ? __ia32_sys_read+0x50/0x50
 ? __audit_syscall_exit+0x3ce/0x450
 do_syscall_64+0x73/0x200
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7ff6f6147c60
Code: 73 01 c3 48 8b 0d 28 12 2d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 5d 73 2d 00 00 75 10 b8 01 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83
RSP: 002b:00007ffd772ead18 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000034 RCX: 00007ff6f6147c60
RDX: 0000000000000034 RSI: 000055df30a31270 RDI: 0000000000000003
RBP: 000055df30a31270 R08: 0000000000000000 R09: 0000000000000000
R10: 00007ffd772ead70 R11: 0000000000000246 R12: 00007ffd772ead74
R13: 00007ffd772eae20 R14: 00007ffd772eae24 R15: 000055df2f12ddc0

Allocated by task 6052:
 kasan_kmalloc+0xa0/0xd0
 __kmalloc+0x10a/0x220
 ops_init+0x97/0x190
 register_pernet_operations+0x1ac/0x360
 register_pernet_subsys+0x24/0x40
 0xffffffffc0ea016d
 do_one_initcall+0x8b/0x253
 do_init_module+0xe3/0x335
 load_module+0x2fc0/0x3890
 __do_sys_finit_module+0x192/0x1c0
 do_syscall_64+0x73/0x200
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 6067:
 __kasan_slab_free+0x130/0x180
 kfree+0x90/0x1a0
 ops_free_list.part.7+0xa6/0xc0
 unregister_pernet_operations+0x18b/0x1f0
 unregister_pernet_subsys+0x1d/0x30
 ip_vs_cleanup+0x1d/0xd2f [ip_vs]
 __x64_sys_delete_module+0x20c/0x300
 do_syscall_64+0x73/0x200
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff8881e9b26600 which belongs to the cache kmalloc-4096 of size 4096
The buggy address is located 2092 bytes inside of 4096-byte region [ffff8881e9b26600, ffff8881e9b27600)
The buggy address belongs to the page:
page:ffffea0007a6c800 count:1 mapcount:0 mapping:ffff888107c0e600 index:0x0 compound_mapcount: 0
flags: 0x17ffffc0008100(slab|head)
raw: 0017ffffc0008100 dead000000000100 dead000000000200 ffff888107c0e600
raw: 0000000000000000 0000000080070007 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

while unregistering ipvs module, ops_free_list calls
__ip_vs_cleanup, then nf_unregister_net_hooks be called to
do remove nf hook entries. It need a RCU period to finish,
however net->ipvs is set to NULL immediately, which will
trigger NULL pointer dereference when a packet is hooked
and handled by ip_vs_in where net->ipvs is dereferenced.

Another scene is ops_free_list call ops_free to free the
net_generic directly while __ip_vs_cleanup finished, then
calling ip_vs_in will triggers use-after-free.

This patch moves nf_unregister_net_hooks from __ip_vs_cleanup()
to __ip_vs_dev_cleanup(),  where rcu_barrier() is called by
unregister_pernet_device -> unregister_pernet_operations,
that will do the needed grace period.

Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: efe4160 ("ipvs: convert to use pernet nf_hook api")
Suggested-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
nathanchance pushed a commit that referenced this issue Sep 18, 2019
@hundeboll @gregkh
tty: n_gsm: avoid recursive locking with async port hangup
7030082 
When tearing down the n_gsm ldisc while one or more of its child ports
are open, a lock dep warning occurs:

[   56.254258] ======================================================
[   56.260447] WARNING: possible circular locking dependency detected
[   56.266641] 5.2.0-00118-g1fd58e20e5b0 #30 Not tainted
[   56.271701] ------------------------------------------------------
[   56.277890] cmux/271 is trying to acquire lock:
[   56.282436] 8215283a (&tty->legacy_mutex){+.+.}, at: __tty_hangup.part.0+0x58/0x27c
[   56.290128]
[   56.290128] but task is already holding lock:
[   56.295970] e9e2b842 (&gsm->mutex){+.+.}, at: gsm_cleanup_mux+0x9c/0x15c
[   56.302699]
[   56.302699] which lock already depends on the new lock.
[   56.302699]
[   56.310884]
[   56.310884] the existing dependency chain (in reverse order) is:
[   56.318372]
[   56.318372] -> #2 (&gsm->mutex){+.+.}:
[   56.323624]        mutex_lock_nested+0x1c/0x24
[   56.328079]        gsm_cleanup_mux+0x9c/0x15c
[   56.332448]        gsmld_ioctl+0x418/0x4e8
[   56.336554]        tty_ioctl+0x96c/0xcb0
[   56.340492]        do_vfs_ioctl+0x41c/0xa5c
[   56.344685]        ksys_ioctl+0x34/0x60
[   56.348535]        ret_fast_syscall+0x0/0x28
[   56.352815]        0xbe97cc04
[   56.355791]
[   56.355791] -> #1 (&tty->ldisc_sem){++++}:
[   56.361388]        tty_ldisc_lock+0x50/0x74
[   56.365581]        tty_init_dev+0x88/0x1c4
[   56.369687]        tty_open+0x1c8/0x430
[   56.373536]        chrdev_open+0xa8/0x19c
[   56.377560]        do_dentry_open+0x118/0x3c4
[   56.381928]        path_openat+0x2fc/0x1190
[   56.386123]        do_filp_open+0x68/0xd4
[   56.390146]        do_sys_open+0x164/0x220
[   56.394257]        kernel_init_freeable+0x328/0x3e4
[   56.399146]        kernel_init+0x8/0x110
[   56.403078]        ret_from_fork+0x14/0x20
[   56.407183]        0x0
[   56.409548]
[   56.409548] -> #0 (&tty->legacy_mutex){+.+.}:
[   56.415402]        __mutex_lock+0x64/0x90c
[   56.419508]        mutex_lock_nested+0x1c/0x24
[   56.423961]        __tty_hangup.part.0+0x58/0x27c
[   56.428676]        gsm_cleanup_mux+0xe8/0x15c
[   56.433043]        gsmld_close+0x48/0x90
[   56.436979]        tty_ldisc_kill+0x2c/0x6c
[   56.441173]        tty_ldisc_release+0x88/0x194
[   56.445715]        tty_release_struct+0x14/0x44
[   56.450254]        tty_release+0x36c/0x43c
[   56.454365]        __fput+0x94/0x1e8

Avoid the warning by doing the port hangup asynchronously.

Signed-off-by: Martin Hundebøll <martin@geanix.com>
Link: https://lore.kernel.org/r/20190822215601.9028-1-martin@geanix.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
nathanchance pushed a commit that referenced this issue Sep 30, 2019
@mhiramat @rostedt
tracing/probe: Fix to check the difference of nr_args before adding p…
d2aea95 
…robe

Steven reported that a test triggered:

==================================================================
 BUG: KASAN: slab-out-of-bounds in trace_kprobe_create+0xa9e/0xe40
 Read of size 8 at addr ffff8880c4f25a48 by task ftracetest/4798

 CPU: 2 PID: 4798 Comm: ftracetest Not tainted 5.3.0-rc6-test+ #30
 Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v03.03 07/14/2016
 Call Trace:
  dump_stack+0x7c/0xc0
  ? trace_kprobe_create+0xa9e/0xe40
  print_address_description+0x6c/0x332
  ? trace_kprobe_create+0xa9e/0xe40
  ? trace_kprobe_create+0xa9e/0xe40
  __kasan_report.cold.6+0x1a/0x3b
  ? trace_kprobe_create+0xa9e/0xe40
  kasan_report+0xe/0x12
  trace_kprobe_create+0xa9e/0xe40
  ? print_kprobe_event+0x280/0x280
  ? match_held_lock+0x1b/0x240
  ? find_held_lock+0xac/0xd0
  ? fs_reclaim_release.part.112+0x5/0x20
  ? lock_downgrade+0x350/0x350
  ? kasan_unpoison_shadow+0x30/0x40
  ? __kasan_kmalloc.constprop.6+0xc1/0xd0
  ? trace_kprobe_create+0xe40/0xe40
  ? trace_kprobe_create+0xe40/0xe40
  create_or_delete_trace_kprobe+0x2e/0x60
  trace_run_command+0xc3/0xe0
  ? trace_panic_handler+0x20/0x20
  ? kasan_unpoison_shadow+0x30/0x40
  trace_parse_run_command+0xdc/0x163
  vfs_write+0xe1/0x240
  ksys_write+0xba/0x150
  ? __ia32_sys_read+0x50/0x50
  ? tracer_hardirqs_on+0x61/0x180
  ? trace_hardirqs_off_caller+0x43/0x110
  ? mark_held_locks+0x29/0xa0
  ? do_syscall_64+0x14/0x260
  do_syscall_64+0x68/0x260

Fix to check the difference of nr_args before adding probe
on existing probes. This also may set the error log index
bigger than the number of command parameters. In that case
it sets the error position is next to the last parameter.

Link: http://lkml.kernel.org/r/156966474783.3478.13217501608215769150.stgit@devnote2

Fixes: ca89bc0 ("tracing/kprobe: Add multi-probe per event support")
Reported-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
nathanchance pushed a commit that referenced this issue Oct 20, 2019
@davem330
netdevsim: Fix error handling in nsim_fib_init and nsim_fib_exit
33902b4 
In nsim_fib_init(), if register_fib_notifier failed, nsim_fib_net_ops
should be unregistered before return.

In nsim_fib_exit(), unregister_fib_notifier should be called before
nsim_fib_net_ops be unregistered, otherwise may cause use-after-free:

BUG: KASAN: use-after-free in nsim_fib_event_nb+0x342/0x570 [netdevsim]
Read of size 8 at addr ffff8881daaf4388 by task kworker/0:3/3499

CPU: 0 PID: 3499 Comm: kworker/0:3 Not tainted 5.3.0-rc7+ #30
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
Workqueue: ipv6_addrconf addrconf_dad_work [ipv6]
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0xa9/0x10e lib/dump_stack.c:113
 print_address_description+0x65/0x380 mm/kasan/report.c:351
 __kasan_report+0x149/0x18d mm/kasan/report.c:482
 kasan_report+0xe/0x20 mm/kasan/common.c:618
 nsim_fib_event_nb+0x342/0x570 [netdevsim]
 notifier_call_chain+0x52/0xf0 kernel/notifier.c:95
 __atomic_notifier_call_chain+0x78/0x140 kernel/notifier.c:185
 call_fib_notifiers+0x30/0x60 net/core/fib_notifier.c:30
 call_fib6_entry_notifiers+0xc1/0x100 [ipv6]
 fib6_add+0x92e/0x1b10 [ipv6]
 __ip6_ins_rt+0x40/0x60 [ipv6]
 ip6_ins_rt+0x84/0xb0 [ipv6]
 __ipv6_ifa_notify+0x4b6/0x550 [ipv6]
 ipv6_ifa_notify+0xa5/0x180 [ipv6]
 addrconf_dad_completed+0xca/0x640 [ipv6]
 addrconf_dad_work+0x296/0x960 [ipv6]
 process_one_work+0x5c0/0xc00 kernel/workqueue.c:2269
 worker_thread+0x5c/0x670 kernel/workqueue.c:2415
 kthread+0x1d7/0x200 kernel/kthread.c:255
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Allocated by task 3388:
 save_stack+0x19/0x80 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 __kasan_kmalloc.constprop.3+0xa0/0xd0 mm/kasan/common.c:493
 kmalloc include/linux/slab.h:557 [inline]
 kzalloc include/linux/slab.h:748 [inline]
 ops_init+0xa9/0x220 net/core/net_namespace.c:127
 __register_pernet_operations net/core/net_namespace.c:1135 [inline]
 register_pernet_operations+0x1d4/0x420 net/core/net_namespace.c:1212
 register_pernet_subsys+0x24/0x40 net/core/net_namespace.c:1253
 nsim_fib_init+0x12/0x70 [netdevsim]
 veth_get_link_ksettings+0x2b/0x50 [veth]
 do_one_initcall+0xd4/0x454 init/main.c:939
 do_init_module+0xe0/0x330 kernel/module.c:3490
 load_module+0x3c2f/0x4620 kernel/module.c:3841
 __do_sys_finit_module+0x163/0x190 kernel/module.c:3931
 do_syscall_64+0x72/0x2e0 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 3534:
 save_stack+0x19/0x80 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 __kasan_slab_free+0x130/0x180 mm/kasan/common.c:455
 slab_free_hook mm/slub.c:1423 [inline]
 slab_free_freelist_hook mm/slub.c:1474 [inline]
 slab_free mm/slub.c:3016 [inline]
 kfree+0xe9/0x2d0 mm/slub.c:3957
 ops_free net/core/net_namespace.c:151 [inline]
 ops_free_list.part.7+0x156/0x220 net/core/net_namespace.c:184
 ops_free_list net/core/net_namespace.c:182 [inline]
 __unregister_pernet_operations net/core/net_namespace.c:1165 [inline]
 unregister_pernet_operations+0x221/0x2a0 net/core/net_namespace.c:1224
 unregister_pernet_subsys+0x1d/0x30 net/core/net_namespace.c:1271
 nsim_fib_exit+0x11/0x20 [netdevsim]
 nsim_module_exit+0x16/0x21 [netdevsim]
 __do_sys_delete_module kernel/module.c:1015 [inline]
 __se_sys_delete_module kernel/module.c:958 [inline]
 __x64_sys_delete_module+0x244/0x330 kernel/module.c:958
 do_syscall_64+0x72/0x2e0 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: 59c84b9 ("netdevsim: Restore per-network namespace accounting for fib entries")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
nathanchance pushed a commit that referenced this issue Dec 2, 2019
@djwong
xfs: periodically yield scrub threads to the scheduler
5d1116d 
Christoph Hellwig complained about the following soft lockup warning
when running scrub after generic/175 when preemption is disabled and
slub debugging is enabled:

watchdog: BUG: soft lockup - CPU#3 stuck for 22s! [xfs_scrub:161]
Modules linked in:
irq event stamp: 41692326
hardirqs last  enabled at (41692325): [<ffffffff8232c3b7>] _raw_0
hardirqs last disabled at (41692326): [<ffffffff81001c5a>] trace0
softirqs last  enabled at (41684994): [<ffffffff8260031f>] __do_e
softirqs last disabled at (41684987): [<ffffffff81127d8c>] irq_e0
CPU: 3 PID: 16189 Comm: xfs_scrub Not tainted 5.4.0-rc3+ #30
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.124
RIP: 0010:_raw_spin_unlock_irqrestore+0x39/0x40
Code: 89 f3 be 01 00 00 00 e8 d5 3a e5 fe 48 89 ef e8 ed 87 e5 f2
RSP: 0018:ffffc9000233f970 EFLAGS: 00000286 ORIG_RAX: ffffffffff3
RAX: ffff88813b398040 RBX: 0000000000000286 RCX: 0000000000000006
RDX: 0000000000000006 RSI: ffff88813b3988c0 RDI: ffff88813b398040
RBP: ffff888137958640 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffea00042b0c00
R13: 0000000000000001 R14: ffff88810ac32308 R15: ffff8881376fc040
FS:  00007f6113dea700(0000) GS:ffff88813bb80000(0000) knlGS:00000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6113de8ff8 CR3: 000000012f290000 CR4: 00000000000006e0
Call Trace:
 free_debug_processing+0x1dd/0x240
 __slab_free+0x231/0x410
 kmem_cache_free+0x30e/0x360
 xchk_ag_btcur_free+0x76/0xb0
 xchk_ag_free+0x10/0x80
 xchk_bmap_iextent_xref.isra.14+0xd9/0x120
 xchk_bmap_iextent+0x187/0x210
 xchk_bmap+0x2e0/0x3b0
 xfs_scrub_metadata+0x2e7/0x500
 xfs_ioc_scrub_metadata+0x4a/0xa0
 xfs_file_ioctl+0x58a/0xcd0
 do_vfs_ioctl+0xa0/0x6f0
 ksys_ioctl+0x5b/0x90
 __x64_sys_ioctl+0x11/0x20
 do_syscall_64+0x4b/0x1a0
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

If preemption is disabled, all metadata buffers needed to perform the
scrub are already in memory, and there are a lot of records to check,
it's possible that the scrub thread will run for an extended period of
time without sleeping for IO or any other reason.  Then the watchdog
timer or the RCU stall timeout can trigger, producing the backtrace
above.

To fix this problem, call cond_resched() from the scrub thread so that
we back out to the scheduler whenever necessary.

Reported-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
@stephenhines stephenhines mentioned this issue Feb 21, 2020
Closed
@nathanchance nathanchance mentioned this issue May 17, 2020
Closed
nathanchance pushed a commit that referenced this issue Jun 26, 2020
@torvalds
mm/memory_hotplug.c: fix false softlockup during pfn range removal
b7e3deb 
When working with very large nodes, poisoning the struct pages (for which
there will be very many) can take a very long time.  If the system is
using voluntary preemptions, the software watchdog will not be able to
detect forward progress.  This patch addresses this issue by offering to
give up time like __remove_pages() does.  This behavior was introduced in
v5.6 with: commit d33695b ("mm/memory_hotplug: poison memmap in
remove_pfn_range_from_zone()")

Alternately, init_page_poison could do this cond_resched(), but it seems
to me that the caller of init_page_poison() is what actually knows whether
or not it should relax its own priority.

Based on Dan's notes, I think this is perfectly safe: commit f931ab4
("mm: fix devm_memremap_pages crash, use mem_hotplug_{begin, done}")

Aside from fixing the lockup, it is also a friendlier thing to do on lower
core systems that might wipe out large chunks of hotplug memory (probably
not a very common case).

Fixes this kind of splat:

  watchdog: BUG: soft lockup - CPU#46 stuck for 22s! [daxctl:9922]
  irq event stamp: 138450
  hardirqs last  enabled at (138449): [<ffffffffa1001f26>] trace_hardirqs_on_thunk+0x1a/0x1c
  hardirqs last disabled at (138450): [<ffffffffa1001f42>] trace_hardirqs_off_thunk+0x1a/0x1c
  softirqs last  enabled at (138448): [<ffffffffa1e00347>] __do_softirq+0x347/0x456
  softirqs last disabled at (138443): [<ffffffffa10c416d>] irq_exit+0x7d/0xb0
  CPU: 46 PID: 9922 Comm: daxctl Not tainted 5.7.0-BEN-14238-g373c6049b336 #30
  Hardware name: Intel Corporation PURLEY/PURLEY, BIOS PLYXCRB1.86B.0578.D07.1902280810 02/28/2019
  RIP: 0010:memset_erms+0x9/0x10
  Code: c1 e9 03 40 0f b6 f6 48 b8 01 01 01 01 01 01 01 01 48 0f af c6 f3 48 ab 89 d1 f3 aa 4c 89 c8 c3 90 49 89 f9 40 88 f0 48 89 d1 <f3> aa 4c 89 c8 c3 90 49 89 fa 40 0f b6 ce 48 b8 01 01 01 01 01 01
  Call Trace:
   remove_pfn_range_from_zone+0x3a/0x380
   memunmap_pages+0x17f/0x280
   release_nodes+0x22a/0x260
   __device_release_driver+0x172/0x220
   device_driver_detach+0x3e/0xa0
   unbind_store+0x113/0x130
   kernfs_fop_write+0xdc/0x1c0
   vfs_write+0xde/0x1d0
   ksys_write+0x58/0xd0
   do_syscall_64+0x5a/0x120
   entry_SYSCALL_64_after_hwframe+0x49/0xb3
  Built 2 zonelists, mobility grouping on.  Total pages: 49050381
  Policy zone: Normal
  Built 3 zonelists, mobility grouping on.  Total pages: 49312525
  Policy zone: Normal

David said: "It really only is an issue for devmem.  Ordinary
hotplugged system memory is not affected (onlined/offlined in memory
block granularity)."

Link: http://lkml.kernel.org/r/20200619231213.1160351-1-ben.widawsky@intel.com
Fixes: commit d33695b ("mm/memory_hotplug: poison memmap in remove_pfn_range_from_zone()")
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Reported-by: "Scargall, Steve" <steve.scargall@intel.com>
Reported-by: Ben Widawsky <ben.widawsky@intel.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
nathanchance pushed a commit that referenced this issue Aug 2, 2020
@idosch @davem330
ipv4: Silence suspicious RCU usage warning
83f3522 
fib_trie_unmerge() is called with RTNL held, but not from an RCU
read-side critical section. This leads to the following warning [1] when
the FIB alias list in a leaf is traversed with
hlist_for_each_entry_rcu().

Since the function is always called with RTNL held and since
modification of the list is protected by RTNL, simply use
hlist_for_each_entry() and silence the warning.

[1]
WARNING: suspicious RCU usage
5.8.0-rc4-custom-01520-gc1f937f3f83b #30 Not tainted
-----------------------------
net/ipv4/fib_trie.c:1867 RCU-list traversed in non-reader section!!

other info that might help us debug this:

rcu_scheduler_active = 2, debug_locks = 1
1 lock held by ip/164:
 #0: ffffffff85a27850 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x49a/0xbd0

stack backtrace:
CPU: 0 PID: 164 Comm: ip Not tainted 5.8.0-rc4-custom-01520-gc1f937f3f83b #30
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-2.fc32 04/01/2014
Call Trace:
 dump_stack+0x100/0x184
 lockdep_rcu_suspicious+0x153/0x15d
 fib_trie_unmerge+0x608/0xdb0
 fib_unmerge+0x44/0x360
 fib4_rule_configure+0xc8/0xad0
 fib_nl_newrule+0x37a/0x1dd0
 rtnetlink_rcv_msg+0x4f7/0xbd0
 netlink_rcv_skb+0x17a/0x480
 rtnetlink_rcv+0x22/0x30
 netlink_unicast+0x5ae/0x890
 netlink_sendmsg+0x98a/0xf40
 ____sys_sendmsg+0x879/0xa00
 ___sys_sendmsg+0x122/0x190
 __sys_sendmsg+0x103/0x1d0
 __x64_sys_sendmsg+0x7d/0xb0
 do_syscall_64+0x54/0xa0
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7fc80a234e97
Code: Bad RIP value.
RSP: 002b:00007ffef8b66798 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc80a234e97
RDX: 0000000000000000 RSI: 00007ffef8b66800 RDI: 0000000000000003
RBP: 000000005f141b1c R08: 0000000000000001 R09: 0000000000000000
R10: 00007fc80a2a8ac0 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000000 R14: 00007ffef8b67008 R15: 0000556fccb10020

Fixes: 0ddcf43 ("ipv4: FIB Local/MAIN table collapse")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
nathanchance pushed a commit that referenced this issue Aug 5, 2020
@biger410 @liu-song-6
md: fix deadlock causing by sysfs_notify
e1a86db 
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>
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[ARCH] x86_64 This bug impacts ARCH=x86_64 [BUG] linux A bug that should be fixed in the mainline kernel. [FIXED][LINUX] 5.1 This bug was fixed in Linux 5.1 [TOOL] lld The issue is relevant to LLD linker
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