Message-ID: <CANp29Y5ujSAQg4_dhoxQQFHeb15Eukkswrzv9uMiZ5m6y6z4uQ@mail.gmail.com>
Date: Fri, 29 Nov 2024 23:16:08 +0100
From: Aleksandr Nogikh <nogikh@...gle.com>
To: Bjorn Helgaas <helgaas@...nel.org>
Cc: syzbot <syzbot+fe139f9822abd9855970@...kaller.appspotmail.com>, 
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, 
	netfs@...ts.linux.dev, syzkaller-bugs@...glegroups.com, v9fs@...ts.linux.dev
Subject: Re: [syzbot] [netfs?] WARNING in netfs_retry_reads

Hi Bjorn,

The "#syz invalid" command tells syzbot that the whole bug report is
just a one-off false positive (that happens sometimes because of
memory corruptions -- the kernel just starts crashing in random
places). The bot then considers that the problem is gone and the next
time it sees a "WARNING in netfs_retry_reads" crash, it will report it
again as a totally new problem "WARNING in netfs_retry_reads (2)" and
so on.

So if it's e.g. just the bisection result that was wrong, while the
crash report itself is legit, it's better to not use the "#syz
invalid" command. I've added +1 to our backlog issue for adding a
special command to cancel only the misleading bisection result [1].

[1] https://github.com/google/syzkaller/issues/3491

-- 
Aleksandr

On Fri, Nov 29, 2024 at 7:51 PM 'Bjorn Helgaas' via syzkaller-bugs
<syzkaller-bugs@...glegroups.com> wrote:
>
> On Thu, Nov 28, 2024 at 11:27:24PM -0800, syzbot wrote:
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit:    85a2dd7d7c81 Add linux-next specific files for 20241125
> > git tree:       linux-next
> > console output: https://syzkaller.appspot.com/x/log.txt?x=10e3a5c0580000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=45719eec4c74e6ba
> > dashboard link: https://syzkaller.appspot.com/bug?extid=fe139f9822abd9855970
> > compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1334dee8580000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14e3a5c0580000
> >
> > Downloadable assets:
> > disk image: https://storage.googleapis.com/syzbot-assets/5422dd6ada68/disk-85a2dd7d.raw.xz
> > vmlinux: https://storage.googleapis.com/syzbot-assets/3a382ed71d3a/vmlinux-85a2dd7d.xz
> > kernel image: https://storage.googleapis.com/syzbot-assets/9b4d03eb0da3/bzImage-85a2dd7d.xz
> >
> > The issue was bisected to:
> >
> > commit fad610b987132868e3410c530871086552ce6155
> > Author: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
> > Date:   Fri Oct 18 14:47:47 2024 +0000
> >
> >     Documentation PCI: Reformat RMW ops documentation
> >
> > bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=16de1530580000
> > final oops:     https://syzkaller.appspot.com/x/report.txt?x=15de1530580000
> > console output: https://syzkaller.appspot.com/x/log.txt?x=11de1530580000
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+fe139f9822abd9855970@...kaller.appspotmail.com
> > Fixes: fad610b98713 ("Documentation PCI: Reformat RMW ops documentation")
>
> #syz invalid
>
> fad610b98713 touches only documentation, so the oops might be an
> intermittent problem elsewhere.  It's not likely to be related to
> fad610b98713; entire commit quoted below:
>
> commit fad610b98713 ("Documentation PCI: Reformat RMW ops documentation")
> Author: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
> Date:   Fri Oct 18 17:47:47 2024 +0300
>
>     Documentation PCI: Reformat RMW ops documentation
>
>     Extract the list of RMW protected PCIe Capability registers into a
>     bullet list to make them easier to pick up on a glance. An upcoming
>     change is going to add one more register among them so it will be much
>     cleaner to have them as bullets.
>
>     Link: https://lore.kernel.org/r/20241018144755.7875-2-ilpo.jarvinen@linux.intel.com
>     Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
>     Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
>     Reviewed-by: Lukas Wunner <lukas@...ner.de>
>     Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
>
>
> diff --git a/Documentation/PCI/pciebus-howto.rst b/Documentation/PCI/pciebus-howto.rst
> index f344452651e1..e48d01422efc 100644
> --- a/Documentation/PCI/pciebus-howto.rst
> +++ b/Documentation/PCI/pciebus-howto.rst
> @@ -217,8 +217,11 @@ capability structure except the PCI Express capability structure,
>  that is shared between many drivers including the service drivers.
>  RMW Capability accessors (pcie_capability_clear_and_set_word(),
>  pcie_capability_set_word(), and pcie_capability_clear_word()) protect
> -a selected set of PCI Express Capability Registers (Link Control
> -Register and Root Control Register). Any change to those registers
> -should be performed using RMW accessors to avoid problems due to
> -concurrent updates. For the up-to-date list of protected registers,
> -see pcie_capability_clear_and_set_word().
> +a selected set of PCI Express Capability Registers:
> +
> +* Link Control Register
> +* Root Control Register
> +
> +Any change to those registers should be performed using RMW accessors to
> +avoid problems due to concurrent updates. For the up-to-date list of
> +protected registers, see pcie_capability_clear_and_set_word().
>
> > ------------[ cut here ]------------
> > do not call blocking ops when !TASK_RUNNING; state=2 set at [<ffffffff8177bd66>] prepare_to_wait+0x186/0x210 kernel/sched/wait.c:237
> > WARNING: CPU: 0 PID: 5848 at kernel/sched/core.c:8685 __might_sleep+0xb9/0xe0 kernel/sched/core.c:8681
> > Modules linked in:
> > CPU: 0 UID: 0 PID: 5848 Comm: syz-executor189 Not tainted 6.12.0-next-20241125-syzkaller #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
> > RIP: 0010:__might_sleep+0xb9/0xe0 kernel/sched/core.c:8681
> > Code: 93 0e 01 90 42 80 3c 23 00 74 08 48 89 ef e8 fe 38 9b 00 48 8b 4d 00 48 c7 c7 80 2d 0a 8c 44 89 ee 48 89 ca e8 b8 e6 f0 ff 90 <0f> 0b 90 90 eb b5 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c 70 ff ff ff
> > RSP: 0018:ffffc90003e465a8 EFLAGS: 00010246
> > RAX: ff5208356e89db00 RBX: 1ffff1100fff22ed RCX: ffff88807ff90000
> > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> > RBP: ffff88807ff91768 R08: ffffffff81601b32 R09: fffffbfff1cfa218
> > R10: dffffc0000000000 R11: fffffbfff1cfa218 R12: dffffc0000000000
> > R13: 0000000000000002 R14: 000000000000004a R15: ffffffff8c1ca120
> > FS:  0000555573787380(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
> > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 00007ff2460a1104 CR3: 00000000745c2000 CR4: 00000000003526f0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > Call Trace:
> >  <TASK>
> >  wait_on_bit include/linux/wait_bit.h:74 [inline]
> >  netfs_retry_reads+0xde/0x1e00 fs/netfs/read_retry.c:263
> >  netfs_collect_read_results fs/netfs/read_collect.c:333 [inline]
> >  netfs_read_collection+0x33a0/0x4070 fs/netfs/read_collect.c:414
> >  netfs_wait_for_read+0x2ba/0x4e0 fs/netfs/read_collect.c:629
> >  netfs_unbuffered_read fs/netfs/direct_read.c:156 [inline]
> >  netfs_unbuffered_read_iter_locked+0x120e/0x1560 fs/netfs/direct_read.c:231
> >  netfs_unbuffered_read_iter+0xbf/0xe0 fs/netfs/direct_read.c:266
> >  __kernel_read+0x513/0x9d0 fs/read_write.c:523
> >  integrity_kernel_read+0xb0/0x100 security/integrity/iint.c:28
> >  ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:480 [inline]
> >  ima_calc_file_shash security/integrity/ima/ima_crypto.c:511 [inline]
> >  ima_calc_file_hash+0xae6/0x1b30 security/integrity/ima/ima_crypto.c:568
> >  ima_collect_measurement+0x520/0xb10 security/integrity/ima/ima_api.c:293
> >  process_measurement+0x1351/0x1fb0 security/integrity/ima/ima_main.c:372
> >  ima_file_check+0xd9/0x120 security/integrity/ima/ima_main.c:572
> >  security_file_post_open+0xb9/0x280 security/security.c:3121
> >  do_open fs/namei.c:3830 [inline]
> >  path_openat+0x2ccd/0x3590 fs/namei.c:3987
> >  do_filp_open+0x27f/0x4e0 fs/namei.c:4014
> >  do_sys_openat2+0x13e/0x1d0 fs/open.c:1402
> >  do_sys_open fs/open.c:1417 [inline]
> >  __do_sys_open fs/open.c:1425 [inline]
> >  __se_sys_open fs/open.c:1421 [inline]
> >  __x64_sys_open+0x225/0x270 fs/open.c:1421
> >  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
> >  do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
> >  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> > RIP: 0033:0x7ff24603d929
> > Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 61 1a 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
> > RSP: 002b:00007ffe9079c548 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
> > RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007ff24603d929
> > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000340
> > RBP: 00007ff24608a257 R08: 0000000000000000 R09: 0000000000000000
> > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000023fb0
> > R13: 00007ff2460bab40 R14: 00007ff2460bcd00 R15: 00007ffe9079c570
> >  </TASK>
> >
> >
> > ---
> > This report is generated by a bot. It may contain errors.
> > See https://goo.gl/tpsmEJ for more information about syzbot.
> > syzbot engineers can be reached at syzkaller@...glegroups.com.
> >
> > syzbot will keep track of this issue. See:
> > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> > For information about bisection process see: https://goo.gl/tpsmEJ#bisection
> >
> > If the report is already addressed, let syzbot know by replying with:
> > #syz fix: exact-commit-title
> >
> > If you want syzbot to run the reproducer, reply with:
> > #syz test: git://repo/address.git branch-or-commit-hash
> > If you attach or paste a git patch, syzbot will apply it before testing.
> >
> > If you want to overwrite report's subsystems, reply with:
> > #syz set subsystems: new-subsystem
> > (See the list of subsystem names on the web dashboard)
> >
> > If the report is a duplicate of another one, reply with:
> > #syz dup: exact-subject-of-another-report
> >
> > If you want to undo deduplication, reply with:
> > #syz undup
>
> --
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