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Subject: Re: WARNING in btrfs_run_delayed_refs
To:     Hao Sun <sunhao.th@gmail.com>, clm@fb.com, dsterba@suse.com,
        Josef Bacik <josef@toxicpanda.com>, linux-btrfs@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org
References: <CACkBjsa0wQ5oDQh0CABfV-UoAa9czS6DAuAA0fBrM_HhVxd6+w@mail.gmail.com>
From:   Qu Wenruo <quwenruo.btrfs@gmx.com>
Message-ID: <a911ac2c-d743-03ea-513d-0b9756808d17@gmx.com>
Date:   Wed, 15 Sep 2021 10:20:36 +0800
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On 2021/9/15 =E4=B8=8A=E5=8D=8810:14, Hao Sun wrote:
> Hello,
>
> When using Healer to fuzz the latest Linux kernel, the following crash
> was triggered.
>
> HEAD commit: 6880fa6c5660 Linux 5.15-rc1
> git tree: upstream
> console output:
> https://drive.google.com/file/d/1gd0dl74MyvvVAYqsCDKSGmcfpZszD0kt/view?u=
sp=3Dsharing
> kernel config: https://drive.google.com/file/d/1rUzyMbe5vcs6khA3tL9EHTLJ=
vsUdWcgB/view?usp=3Dsharing
> C reproducer: https://drive.google.com/file/d/1WKQukijOJ7D0NYk1iKf47FESj=
YfAjrlz/view?usp=3Dsharing
> Syzlang reproducer:
> https://drive.google.com/file/d/1Gi9-Mgbrjw1OI-ymO4zDVIFej2Qf4ppL/view?u=
sp=3Dsharing
>
> If you fix this issue, please add the following tag to the commit:
> Reported-by: Hao Sun <sunhao.th@gmail.com>
>
> loop11: detected capacity change from 0 to 32768
> BTRFS info (device loop11): disk space caching is enabled
> BTRFS info (device loop11): has skinny extents
> BTRFS info (device loop11): enabling ssd optimizations
> FAULT_INJECTION: forcing a failure.
> name failslab, interval 1, probability 0, space 0, times 0
> CPU: 0 PID: 7769 Comm: syz-executor Not tainted 5.15.0-rc1 #16
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
> Call Trace:
>   __dump_stack lib/dump_stack.c:88 [inline]
>   dump_stack_lvl+0x8d/0xcf lib/dump_stack.c:106
>   fail_dump lib/fault-inject.c:52 [inline]
>   should_fail+0x13c/0x160 lib/fault-inject.c:146
>   should_failslab+0x5/0x10 mm/slab_common.c:1328
>   slab_pre_alloc_hook.constprop.99+0x4e/0xc0 mm/slab.h:494
>   slab_alloc_node mm/slub.c:3120 [inline]
>   slab_alloc mm/slub.c:3214 [inline]
>   kmem_cache_alloc+0x44/0x280 mm/slub.c:3219
>   __btrfs_free_extent.isra.53+0x7b/0x1180 fs/btrfs/extent-tree.c:2942
>   run_delayed_tree_ref fs/btrfs/extent-tree.c:1687 [inline]
>   run_one_delayed_ref fs/btrfs/extent-tree.c:1711 [inline]
>   btrfs_run_delayed_refs_for_head fs/btrfs/extent-tree.c:1952 [inline]
>   __btrfs_run_delayed_refs+0x83e/0x1a00 fs/btrfs/extent-tree.c:2017
>   btrfs_run_delayed_refs+0xb1/0x2b0 fs/btrfs/extent-tree.c:2148
>   btrfs_commit_transaction+0x7d/0x1430 fs/btrfs/transaction.c:2065
>   btrfs_sync_fs+0x9a/0x430 fs/btrfs/super.c:1426
>   btrfs_ioctl+0x209b/0x3be0 fs/btrfs/ioctl.c:4970
>   vfs_ioctl fs/ioctl.c:51 [inline]
>   __do_sys_ioctl fs/ioctl.c:874 [inline]
>   __se_sys_ioctl fs/ioctl.c:860 [inline]
>   __x64_sys_ioctl+0xb6/0x100 fs/ioctl.c:860
>   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>   do_syscall_64+0x34/0xb0 arch/x86/entry/common.c:80
>   entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x46ae99
> Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 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 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007f8ac08c7c48 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> RAX: ffffffffffffffda RBX: 000000000078c0a0 RCX: 000000000046ae99
> RDX: 0000000000000000 RSI: 0000000000009408 RDI: 0000000000000003
> RBP: 00007f8ac08c7c80 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
> R13: 0000000000000000 R14: 000000000078c0a0 R15: 00007ffccc1d6390
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 7769 at fs/btrfs/extent-tree.c:2150
> btrfs_run_delayed_refs+0x245/0x2b0 fs/btrfs/extent-tree.c:2150

This is again btrfs_abort_transaction().

This makes me wonder, should we add ENOMEM to abort transaction warning
condition to make the ENOMEM injection code happy.

Mind to test the following diff?

Thanks,
Qu

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 8c6ee947a68d..6bc79f6716fa 100644
=2D-- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3548,7 +3548,8 @@ do {
                 \
         /* Report first abort since mount */                    \
         if (!test_and_set_bit(BTRFS_FS_STATE_TRANS_ABORTED,     \
                         &((trans)->fs_info->fs_state))) {       \
-               if ((errno) !=3D -EIO && (errno) !=3D -EROFS) {           =
  \
+               if ((errno) !=3D -EIO && (errno) !=3D -EROFS &&     \
+                   (errno) !=3D -ENOMEM) {                       \
                         WARN(1, KERN_DEBUG                              \
                         "BTRFS: Transaction aborted (error %d)\n",      \
                         (errno));                                       \

> Modules linked in:
> CPU: 0 PID: 7769 Comm: syz-executor Not tainted 5.15.0-rc1 #16
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
> RIP: 0010:btrfs_run_delayed_refs+0x245/0x2b0 fs/btrfs/extent-tree.c:2150
> Code: 72 2d e8 ce a4 4d ff 8b 04 24 83 f8 fb 74 49 83 f8 e2 74 44 e8
> bc a4 4d ff 8b 04 24 48 c7 c7 38 25 39 85 89 c6 e8 db ab 38 ff <0f> 0b
> 8b 04 24 89 04 24 e8 9e a4 4d ff 8b 04 24 ba 66 08 00 00 4c
> RSP: 0018:ffffc9000509bcc8 EFLAGS: 00010286
> RAX: 0000000000000000 RBX: ffff888014054000 RCX: ffffc9000cb3c000
> RDX: 0000000000040000 RSI: ffffffff812d18bc RDI: 00000000ffffffff
> RBP: ffff888014054000 R08: 0000000000000000 R09: 0000000000000001
> R10: 0000000000000000 R11: 0000000000000000 R12: ffff88801f13e800
> R13: ffff8880091b2000 R14: ffff88801f13e800 R15: 0000000000000000
> FS:  00007f8ac08c8700(0000) GS:ffff88813dc00000(0000) knlGS:000000000000=
0000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fc39085b000 CR3: 000000010e194000 CR4: 0000000000750ee0
> DR0: 0000000000003000 DR1: 0000000000001000 DR2: 0000000000010000
> DR3: 000000000000d000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> PKRU: 55555554
> Call Trace:
>   btrfs_commit_transaction+0x7d/0x1430 fs/btrfs/transaction.c:2065
>   btrfs_sync_fs+0x9a/0x430 fs/btrfs/super.c:1426
>   btrfs_ioctl+0x209b/0x3be0 fs/btrfs/ioctl.c:4970
>   vfs_ioctl fs/ioctl.c:51 [inline]
>   __do_sys_ioctl fs/ioctl.c:874 [inline]
>   __se_sys_ioctl fs/ioctl.c:860 [inline]
>   __x64_sys_ioctl+0xb6/0x100 fs/ioctl.c:860
>   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>   do_syscall_64+0x34/0xb0 arch/x86/entry/common.c:80
>   entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x46ae99
> Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 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 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007f8ac08c7c48 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> RAX: ffffffffffffffda RBX: 000000000078c0a0 RCX: 000000000046ae99
> RDX: 0000000000000000 RSI: 0000000000009408 RDI: 0000000000000003
> RBP: 00007f8ac08c7c80 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
> R13: 0000000000000000 R14: 000000000078c0a0 R15: 00007ffccc1d6390
>