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Kent Overstreet and others added 14 commits December 3, 2023 12:44
There's no need to drop journal pins in our exit paths - the code was
trying to have everything cleaned up on any shutdown, but better to just
tweak the assertions a bit.

This fixes a bug where calling into journal reclaim in the exit path
would cass a null ptr deref.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
The keys being replayed by journal replay have to be synchronized with
updates by other threads that overwrite them. We rely on btree node
locks for synchronizing - but since btree write buffer updates take no
btree locks, that won't work.

Instead, simply disable using the btree write buffer until journal
replay is finished.

This fixes a rare backpointers error in the merge_torture_flakey test.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Recently, journal pre-reservations were removed. They were for reserving
space ahead of time in the journal for operations that are required for
journal reclaim, e.g. btree key cache flushing and interior node btree
updates.

Instead we have watermarks - only operations for journal reclaim are
allowed when the journal is low on space, and in general we're quite
good about doing operations in the order that will free up space in the
journal quickest when we're low on space. If we're doing a journal
reclaim operation out of order, we usually do it in nonblocking mode if
it's not freeing up space at the end of the journal.

There's an exceptino though - interior btree node update operations have
to be BCH_WATERMARK_reclaim - once they've been started, and they can't
be nonblocking. Generally this is fine because they'll only be a very
small fraction of transaction commits - but there's an exception, which
is during journal replay.

Journal replay does many btree operations, but doesn't need to commit
them to the journal since they're already in the journal. So killing off
of pre-reservation, plus another change to make journal replay more
efficient by initially doing the replay in sorted btree order, made it
possible for the interior update operations replay generates to fill and
deadlock the journal.

Fix this by introducing a new check on journal space at the _start_ of
an interior update operation. This causes us to block if necessary in
exactly the same way as we used to when interior updates took a journal
pre-reservaiton, but without all the expensive accounting
pre-reservations required.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Also, make bch2_extent_drop_ptrs() safer, so it works with extents and
non-extents iterators.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
for_each_btree_key2() runs each loop iteration in a btree transaction,
and thus does not cause SRCU lock hold time problems.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This fixes a transaction path overflow reported in the snapshot deletion
path, when moving extents to the correct snapshot.

The root of the issue is that creating/deleting a reflink pointer can
generate an unbounded number of updates, if it is allowed to reference
an unbounded number of indirect extents; to prevent this, merging of
reflink pointers has been disabled.

But there's a hole, which is that copygc/rebalance may fragment existing
extents in the course of moving them around, and if an indirect extent
becomes too fragmented we'll then become unable to delete the reflink
pointer.

The eventual solution is going to be to tweak trigger handling so that
we can process large reflink pointers incrementally when necessary, and
notice that trigger updates don't need to be run for the part of the
reflink pointer not changing. That is going to be a bigger project
though, for another patch.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
When creating a snapshot without specifying the source subvolume, we use
the subvolume containing the new snapshot.

Previously, this worked if the directory containing the new snapshot was
the subvolume root - but we were using the incorrect helper, and got a
subvolume ID of 0 when the parent directory wasn't the root of the
subvolume, causing an emergency read-only.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
The internal freeze mechanism in bcachefs mostly reuses the generic
rw<->ro transition code. If the fs happens to shutdown during or
after freeze, a transition back to rw can fail. This is expected,
but returning an error from the unfreeze callout prevents the
filesystem from being unfrozen.

Skip the read write transition if the fs is shutdown. This allows
the fs to unfreeze at the vfs level so writes will no longer block,
but will still fail due to the emergency read-only state of the fs.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This fixes a bug where rebalance would loop repeatedly on the same
extents.

Signed-off-by: Daniel Hill <daniel@gluo.nz>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
We could delete directories transactionally on rmdir()/unlink(), but we
don't; instead, like with regular files we wait for the VFS to call
evict().

That means that our check for directories in the deleted inodes btree is
wrong - the check should be for non-empty directories.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Since outstanding journal buffers hold a journal pin, when flushing all
pins we need to close the current journal entry if necessary so its pin
can be released.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
If an AFS cell that has an unreachable (eg. ENETUNREACH) server listed (VL
server or fileserver), an asynchronous probe to one of its addresses may
fail immediately because sendmsg() returns an error.  When this happens, a
refcount underflow can happen if certain events hit a very small window.

The way this occurs is:

 (1) There are two levels of "call" object, the afs_call and the
     rxrpc_call.  Each of them can be transitioned to a "completed" state
     in the event of success or failure.

 (2) Asynchronous afs_calls are self-referential whilst they are active to
     prevent them from evaporating when they're not being processed.  This
     reference is disposed of when the afs_call is completed.

     Note that an afs_call may only be completed once; once completed
     completing it again will do nothing.

 (3) When a call transmission is made, the app-side rxrpc code queues a Tx
     buffer for the rxrpc I/O thread to transmit.  The I/O thread invokes
     sendmsg() to transmit it - and in the case of failure, it transitions
     the rxrpc_call to the completed state.

 (4) When an rxrpc_call is completed, the app layer is notified.  In this
     case, the app is kafs and it schedules a work item to process events
     pertaining to an afs_call.

 (5) When the afs_call event processor is run, it goes down through the
     RPC-specific handler to afs_extract_data() to retrieve data from rxrpc
     - and, in this case, it picks up the error from the rxrpc_call and
     returns it.

     The error is then propagated to the afs_call and that is completed
     too.  At this point the self-reference is released.

 (6) If the rxrpc I/O thread manages to complete the rxrpc_call within the
     window between rxrpc_send_data() queuing the request packet and
     checking for call completion on the way out, then
     rxrpc_kernel_send_data() will return the error from sendmsg() to the
     app.

 (7) Then afs_make_call() will see an error and will jump to the error
     handling path which will attempt to clean up the afs_call.

 (8) The problem comes when the error handling path in afs_make_call()
     tries to unconditionally drop an async afs_call's self-reference.
     This self-reference, however, may already have been dropped by
     afs_extract_data() completing the afs_call

 (9) The refcount underflows when we return to afs_do_probe_vlserver() and
     that tries to drop its reference on the afs_call.

Fix this by making afs_make_call() attempt to complete the afs_call rather
than unconditionally putting it.  That way, if afs_extract_data() manages
to complete the call first, afs_make_call() won't do anything.

The bug can be forced by making do_udp_sendmsg() return -ENETUNREACH and
sticking an msleep() in rxrpc_send_data() after the 'success:' label to
widen the race window.

The error message looks something like:

    refcount_t: underflow; use-after-free.
    WARNING: CPU: 3 PID: 720 at lib/refcount.c:28 refcount_warn_saturate+0xba/0x110
    ...
    RIP: 0010:refcount_warn_saturate+0xba/0x110
    ...
    afs_put_call+0x1dc/0x1f0 [kafs]
    afs_fs_get_capabilities+0x8b/0xe0 [kafs]
    afs_fs_probe_fileserver+0x188/0x1e0 [kafs]
    afs_lookup_server+0x3bf/0x3f0 [kafs]
    afs_alloc_server_list+0x130/0x2e0 [kafs]
    afs_create_volume+0x162/0x400 [kafs]
    afs_get_tree+0x266/0x410 [kafs]
    vfs_get_tree+0x25/0xc0
    fc_mount+0xe/0x40
    afs_d_automount+0x1b3/0x390 [kafs]
    __traverse_mounts+0x8f/0x210
    step_into+0x340/0x760
    path_openat+0x13a/0x1260
    do_filp_open+0xaf/0x160
    do_sys_openat2+0xaf/0x170

or something like:

    refcount_t: underflow; use-after-free.
    ...
    RIP: 0010:refcount_warn_saturate+0x99/0xda
    ...
    afs_put_call+0x4a/0x175
    afs_send_vl_probes+0x108/0x172
    afs_select_vlserver+0xd6/0x311
    afs_do_cell_detect_alias+0x5e/0x1e9
    afs_cell_detect_alias+0x44/0x92
    afs_validate_fc+0x9d/0x134
    afs_get_tree+0x20/0x2e6
    vfs_get_tree+0x1d/0xc9
    fc_mount+0xe/0x33
    afs_d_automount+0x48/0x9d
    __traverse_mounts+0xe0/0x166
    step_into+0x140/0x274
    open_last_lookups+0x1c1/0x1df
    path_openat+0x138/0x1c3
    do_filp_open+0x55/0xb4
    do_sys_openat2+0x6c/0xb6

Fixes: 34fa476 ("afs: Fix race in async call refcounting")
Reported-by: Bill MacAllister <bill@ca-zephyr.org>
Closes: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1052304
Suggested-by: Jeffrey E Altman <jaltman@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeffrey Altman <jaltman@auristor.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: https://lore.kernel.org/r/2633992.1702073229@warthog.procyon.org.uk/ # v1
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
…hefs

Pull more bcachefs bugfixes from Kent Overstreet:

 - Fix a rare emergency shutdown path bug: dropping journal pins after
   the filesystem has mostly been torn down is not what we want.

 - Fix some concurrency issues with the btree write buffer and journal
   replay by not using the btree write buffer until journal replay is
   finished

 - A fixup from the prior patch to kill journal pre-reservations: at the
   start of the btree update path, where previously we took a
   pre-reservation, we do at least want to check the journal watermark.

 - Fix a race between dropping device metadata and btree node writes,
   which would re-add a pointer to a device that had just been dropped

 - Fix one of the SCRU lock warnings, in
   bch2_compression_stats_to_text().

 - Partial fix for a rare transaction paths overflow, when indirect
   extents had been split by background tasks, by not running certain
   triggers when they're not needed.

 - Fix for creating a snapshot with implicit source in a subdirectory of
   the containing subvolume

 - Don't unfreeze when we're emergency read-only

 - Fix for rebalance spinning trying to compress unwritten extentns

 - Another deleted_inodes fix, for directories

 - Fix a rare deadlock (usually just an unecessary wait) when flushing
   the journal with an open journal entry.

* tag 'bcachefs-2023-12-10' of https://evilpiepirate.org/git/bcachefs:
  bcachefs: Close journal entry if necessary when flushing all pins
  bcachefs: Fix uninitialized var in bch2_journal_replay()
  bcachefs: Fix deleted inode check for dirs
  bcachefs: rebalance shouldn't attempt to compress unwritten extents
  bcachefs: don't attempt rw on unfreeze when shutdown
  bcachefs: Fix creating snapshot with implict source
  bcachefs: Don't run indirect extent trigger unless inserting/deleting
  bcachefs: Convert compression_stats to for_each_btree_key2
  bcachefs: Fix bch2_extent_drop_ptrs() call
  bcachefs: Fix a journal deadlock in replay
  bcachefs; Don't use btree write buffer until journal replay is finished
  bcachefs: Don't drop journal pins in exit path
@pull pull bot added the ⤵️ pull label Dec 12, 2023
@pull pull bot merged commit 26aff84 into souparna21:master Dec 12, 2023
pull bot pushed a commit that referenced this pull request Mar 29, 2024
A64_LDRSW() takes three registers: Xt, Xn, Xm as arguments and it loads
and sign extends the value at address Xn + Xm into register Xt.

Currently, the offset is being directly used in place of the tmp
register which has the offset already loaded by the last emitted
instruction.

This will cause JIT failures. The easiest way to reproduce this is to
test the following code through test_bpf module:

{
	"BPF_LDX_MEMSX | BPF_W",
	.u.insns_int = {
		BPF_LD_IMM64(R1, 0x00000000deadbeefULL),
		BPF_LD_IMM64(R2, 0xffffffffdeadbeefULL),
		BPF_STX_MEM(BPF_DW, R10, R1, -7),
		BPF_LDX_MEMSX(BPF_W, R0, R10, -7),
		BPF_JMP_REG(BPF_JNE, R0, R2, 1),
		BPF_ALU64_IMM(BPF_MOV, R0, 0),
		BPF_EXIT_INSN(),
	},
	INTERNAL,
	{ },
	{ { 0, 0 } },
	.stack_depth = 7,
},

We need to use the offset as -7 to trigger this code path, there could
be other valid ways to trigger this from proper BPF programs as well.

This code is rejected by the JIT because -7 is passed to A64_LDRSW() but
it expects a valid register (0 - 31).

 roott@pjy:~# modprobe test_bpf test_name="BPF_LDX_MEMSX | BPF_W"
 [11300.490371] test_bpf: test_bpf: set 'test_bpf' as the default test_suite.
 [11300.491750] test_bpf: #345 BPF_LDX_MEMSX | BPF_W
 [11300.493179] aarch64_insn_encode_register: unknown register encoding -7
 [11300.494133] aarch64_insn_encode_register: unknown register encoding -7
 [11300.495292] FAIL to select_runtime err=-524
 [11300.496804] test_bpf: Summary: 0 PASSED, 1 FAILED, [0/0 JIT'ed]
 modprobe: ERROR: could not insert 'test_bpf': Invalid argument

Applying this patch fixes the issue.

 root@pjy:~# modprobe test_bpf test_name="BPF_LDX_MEMSX | BPF_W"
 [  292.837436] test_bpf: test_bpf: set 'test_bpf' as the default test_suite.
 [  292.839416] test_bpf: #345 BPF_LDX_MEMSX | BPF_W jited:1 156 PASS
 [  292.844794] test_bpf: Summary: 1 PASSED, 0 FAILED, [1/1 JIT'ed]

Fixes: cc88f54 ("bpf, arm64: Support sign-extension load instructions")
Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
Message-ID: <20240312235917.103626-1-puranjay12@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
pull bot pushed a commit that referenced this pull request May 17, 2024
Recent additions in BPF like cpu v4 instructions, test_bpf module
exhibits the following failures:

  test_bpf: #82 ALU_MOVSX | BPF_B jited:1 ret 2 != 1 (0x2 != 0x1)FAIL (1 times)
  test_bpf: #83 ALU_MOVSX | BPF_H jited:1 ret 2 != 1 (0x2 != 0x1)FAIL (1 times)
  test_bpf: #84 ALU64_MOVSX | BPF_B jited:1 ret 2 != 1 (0x2 != 0x1)FAIL (1 times)
  test_bpf: #85 ALU64_MOVSX | BPF_H jited:1 ret 2 != 1 (0x2 != 0x1)FAIL (1 times)
  test_bpf: #86 ALU64_MOVSX | BPF_W jited:1 ret 2 != 1 (0x2 != 0x1)FAIL (1 times)

  test_bpf: #165 ALU_SDIV_X: -6 / 2 = -3 jited:1 ret 2147483645 != -3 (0x7ffffffd != 0xfffffffd)FAIL (1 times)
  test_bpf: #166 ALU_SDIV_K: -6 / 2 = -3 jited:1 ret 2147483645 != -3 (0x7ffffffd != 0xfffffffd)FAIL (1 times)

  test_bpf: #169 ALU_SMOD_X: -7 % 2 = -1 jited:1 ret 1 != -1 (0x1 != 0xffffffff)FAIL (1 times)
  test_bpf: #170 ALU_SMOD_K: -7 % 2 = -1 jited:1 ret 1 != -1 (0x1 != 0xffffffff)FAIL (1 times)

  test_bpf: #172 ALU64_SMOD_K: -7 % 2 = -1 jited:1 ret 1 != -1 (0x1 != 0xffffffff)FAIL (1 times)

  test_bpf: #313 BSWAP 16: 0x0123456789abcdef -> 0xefcd
  eBPF filter opcode 00d7 (@2) unsupported
  jited:0 301 PASS
  test_bpf: #314 BSWAP 32: 0x0123456789abcdef -> 0xefcdab89
  eBPF filter opcode 00d7 (@2) unsupported
  jited:0 555 PASS
  test_bpf: #315 BSWAP 64: 0x0123456789abcdef -> 0x67452301
  eBPF filter opcode 00d7 (@2) unsupported
  jited:0 268 PASS
  test_bpf: #316 BSWAP 64: 0x0123456789abcdef >> 32 -> 0xefcdab89
  eBPF filter opcode 00d7 (@2) unsupported
  jited:0 269 PASS
  test_bpf: #317 BSWAP 16: 0xfedcba9876543210 -> 0x1032
  eBPF filter opcode 00d7 (@2) unsupported
  jited:0 460 PASS
  test_bpf: #318 BSWAP 32: 0xfedcba9876543210 -> 0x10325476
  eBPF filter opcode 00d7 (@2) unsupported
  jited:0 320 PASS
  test_bpf: #319 BSWAP 64: 0xfedcba9876543210 -> 0x98badcfe
  eBPF filter opcode 00d7 (@2) unsupported
  jited:0 222 PASS
  test_bpf: #320 BSWAP 64: 0xfedcba9876543210 >> 32 -> 0x10325476
  eBPF filter opcode 00d7 (@2) unsupported
  jited:0 273 PASS

  test_bpf: #344 BPF_LDX_MEMSX | BPF_B
  eBPF filter opcode 0091 (@5) unsupported
  jited:0 432 PASS
  test_bpf: #345 BPF_LDX_MEMSX | BPF_H
  eBPF filter opcode 0089 (@5) unsupported
  jited:0 381 PASS
  test_bpf: #346 BPF_LDX_MEMSX | BPF_W
  eBPF filter opcode 0081 (@5) unsupported
  jited:0 505 PASS

  test_bpf: #490 JMP32_JA: Unconditional jump: if (true) return 1
  eBPF filter opcode 0006 (@1) unsupported
  jited:0 261 PASS

  test_bpf: Summary: 1040 PASSED, 10 FAILED, [924/1038 JIT'ed]

Fix them by adding missing processing.

Fixes: daabb2b ("bpf/tests: add tests for cpuv4 instructions")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/91de862dda99d170697eb79ffb478678af7e0b27.1709652689.git.christophe.leroy@csgroup.eu
pull bot pushed a commit that referenced this pull request Jun 1, 2024
Add a test case to assert that the skb->pkt_type which was set from the BPF
program is retained from the netkit xmit side to the peer's device at tcx
ingress location.

  # ./vmtest.sh -- ./test_progs -t netkit
  [...]
  ./test_progs -t netkit
  [    1.140780] bpf_testmod: loading out-of-tree module taints kernel.
  [    1.141127] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel
  [    1.284601] tsc: Refined TSC clocksource calibration: 3408.006 MHz
  [    1.286672] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x311fd9b189d, max_idle_ns: 440795225691 ns
  [    1.290384] clocksource: Switched to clocksource tsc
  #345     tc_netkit_basic:OK
  #346     tc_netkit_device:OK
  #347     tc_netkit_multi_links:OK
  #348     tc_netkit_multi_opts:OK
  #349     tc_netkit_neigh_links:OK
  #350     tc_netkit_pkt_type:OK
  Summary: 6/0 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20240524163619.26001-4-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
pull bot pushed a commit that referenced this pull request Jul 12, 2024
Add a test case which replaces an active ingress qdisc while keeping the
miniq in-tact during the transition period to the new clsact qdisc.

  # ./vmtest.sh -- ./test_progs -t tc_link
  [...]
  ./test_progs -t tc_link
  [    3.412871] bpf_testmod: loading out-of-tree module taints kernel.
  [    3.413343] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel
  #332     tc_links_after:OK
  #333     tc_links_append:OK
  #334     tc_links_basic:OK
  #335     tc_links_before:OK
  #336     tc_links_chain_classic:OK
  #337     tc_links_chain_mixed:OK
  #338     tc_links_dev_chain0:OK
  #339     tc_links_dev_cleanup:OK
  #340     tc_links_dev_mixed:OK
  #341     tc_links_ingress:OK
  #342     tc_links_invalid:OK
  #343     tc_links_prepend:OK
  #344     tc_links_replace:OK
  #345     tc_links_revision:OK
  Summary: 14/0 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20240708133130.11609-2-daniel@iogearbox.net
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
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3 participants