* [Bug 207711] New: xfs: data race on ctx->space_used in xlog_cil_insert_items()
@ 2020-05-13 2:45 bugzilla-daemon
2020-05-13 4:07 ` Dave Chinner
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: bugzilla-daemon @ 2020-05-13 2:45 UTC (permalink / raw)
To: linux-xfs
https://bugzilla.kernel.org/show_bug.cgi?id=207711
Bug ID: 207711
Summary: xfs: data race on ctx->space_used in
xlog_cil_insert_items()
Product: File System
Version: 2.5
Kernel Version: 5.4
Hardware: All
OS: Linux
Tree: Mainline
Status: NEW
Severity: normal
Priority: P1
Component: XFS
Assignee: filesystem_xfs@kernel-bugs.kernel.org
Reporter: baijiaju1990@gmail.com
Regression: No
The functions xlog_cil_insert_items() and xlog_cil_push_background() are
concurrently executed at runtime at the following call contexts:
Thread 1:
xfs_file_write_iter()
xfs_file_buffered_aio_write()
xfs_file_aio_write_checks()
xfs_vn_update_time()
xfs_trans_commit()
__xfs_trans_commit()
xfs_log_commit_cil()
xlog_cil_insert_items()
Thread 2:
xfs_file_write_iter()
xfs_file_buffered_aio_write()
xfs_file_aio_write_checks()
xfs_vn_update_time()
xfs_trans_commit()
__xfs_trans_commit()
xfs_log_commit_cil()
xlog_cil_push_background()
In xlog_cil_insert_items():
ctx->space_used += len;
In xlog_cil_push_background():
if (cil->xc_ctx->space_used < XLOG_CIL_SPACE_LIMIT(log))
The variables ctx->space_used and cil->xc_ctx->space_used access the same
memory, and thus a data race can occur.
This data race was found and actually reproduced by our concurrency fuzzer.
I am not sure whether this data race is harmful and how to fix this data race
properly, so I want to listen to your opinions, thanks :)
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^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [Bug 207711] New: xfs: data race on ctx->space_used in xlog_cil_insert_items()
2020-05-13 2:45 [Bug 207711] New: xfs: data race on ctx->space_used in xlog_cil_insert_items() bugzilla-daemon
@ 2020-05-13 4:07 ` Dave Chinner
2020-05-13 4:07 ` [Bug 207711] " bugzilla-daemon
2020-05-13 8:00 ` bugzilla-daemon
2 siblings, 0 replies; 4+ messages in thread
From: Dave Chinner @ 2020-05-13 4:07 UTC (permalink / raw)
To: bugzilla-daemon; +Cc: linux-xfs
On Wed, May 13, 2020 at 02:45:54AM +0000, bugzilla-daemon@bugzilla.kernel.org wrote:
> https://bugzilla.kernel.org/show_bug.cgi?id=207711
>
> Bug ID: 207711
> Summary: xfs: data race on ctx->space_used in
> xlog_cil_insert_items()
> Product: File System
> Version: 2.5
> Kernel Version: 5.4
> Hardware: All
> OS: Linux
> Tree: Mainline
> Status: NEW
> Severity: normal
> Priority: P1
> Component: XFS
> Assignee: filesystem_xfs@kernel-bugs.kernel.org
> Reporter: baijiaju1990@gmail.com
> Regression: No
>
> The functions xlog_cil_insert_items() and xlog_cil_push_background() are
> concurrently executed at runtime at the following call contexts:
>
> Thread 1:
> xfs_file_write_iter()
> xfs_file_buffered_aio_write()
> xfs_file_aio_write_checks()
> xfs_vn_update_time()
> xfs_trans_commit()
> __xfs_trans_commit()
> xfs_log_commit_cil()
> xlog_cil_insert_items()
>
> Thread 2:
> xfs_file_write_iter()
> xfs_file_buffered_aio_write()
> xfs_file_aio_write_checks()
> xfs_vn_update_time()
> xfs_trans_commit()
> __xfs_trans_commit()
> xfs_log_commit_cil()
> xlog_cil_push_background()
>
> In xlog_cil_insert_items():
> ctx->space_used += len;
>
> In xlog_cil_push_background():
> if (cil->xc_ctx->space_used < XLOG_CIL_SPACE_LIMIT(log))
Intentionally racy accounting check as it's not critical to be
perfectly accurate here.
Not a bug, please close.
-Dave.
--
Dave Chinner
david@fromorbit.com
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug 207711] xfs: data race on ctx->space_used in xlog_cil_insert_items()
2020-05-13 2:45 [Bug 207711] New: xfs: data race on ctx->space_used in xlog_cil_insert_items() bugzilla-daemon
2020-05-13 4:07 ` Dave Chinner
@ 2020-05-13 4:07 ` bugzilla-daemon
2020-05-13 8:00 ` bugzilla-daemon
2 siblings, 0 replies; 4+ messages in thread
From: bugzilla-daemon @ 2020-05-13 4:07 UTC (permalink / raw)
To: linux-xfs
https://bugzilla.kernel.org/show_bug.cgi?id=207711
--- Comment #1 from Dave Chinner (david@fromorbit.com) ---
On Wed, May 13, 2020 at 02:45:54AM +0000, bugzilla-daemon@bugzilla.kernel.org
wrote:
> https://bugzilla.kernel.org/show_bug.cgi?id=207711
>
> Bug ID: 207711
> Summary: xfs: data race on ctx->space_used in
> xlog_cil_insert_items()
> Product: File System
> Version: 2.5
> Kernel Version: 5.4
> Hardware: All
> OS: Linux
> Tree: Mainline
> Status: NEW
> Severity: normal
> Priority: P1
> Component: XFS
> Assignee: filesystem_xfs@kernel-bugs.kernel.org
> Reporter: baijiaju1990@gmail.com
> Regression: No
>
> The functions xlog_cil_insert_items() and xlog_cil_push_background() are
> concurrently executed at runtime at the following call contexts:
>
> Thread 1:
> xfs_file_write_iter()
> xfs_file_buffered_aio_write()
> xfs_file_aio_write_checks()
> xfs_vn_update_time()
> xfs_trans_commit()
> __xfs_trans_commit()
> xfs_log_commit_cil()
> xlog_cil_insert_items()
>
> Thread 2:
> xfs_file_write_iter()
> xfs_file_buffered_aio_write()
> xfs_file_aio_write_checks()
> xfs_vn_update_time()
> xfs_trans_commit()
> __xfs_trans_commit()
> xfs_log_commit_cil()
> xlog_cil_push_background()
>
> In xlog_cil_insert_items():
> ctx->space_used += len;
>
> In xlog_cil_push_background():
> if (cil->xc_ctx->space_used < XLOG_CIL_SPACE_LIMIT(log))
Intentionally racy accounting check as it's not critical to be
perfectly accurate here.
Not a bug, please close.
-Dave.
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^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug 207711] xfs: data race on ctx->space_used in xlog_cil_insert_items()
2020-05-13 2:45 [Bug 207711] New: xfs: data race on ctx->space_used in xlog_cil_insert_items() bugzilla-daemon
2020-05-13 4:07 ` Dave Chinner
2020-05-13 4:07 ` [Bug 207711] " bugzilla-daemon
@ 2020-05-13 8:00 ` bugzilla-daemon
2 siblings, 0 replies; 4+ messages in thread
From: bugzilla-daemon @ 2020-05-13 8:00 UTC (permalink / raw)
To: linux-xfs
https://bugzilla.kernel.org/show_bug.cgi?id=207711
Jia-Ju Bai (baijiaju1990@gmail.com) changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |INVALID
--- Comment #2 from Jia-Ju Bai (baijiaju1990@gmail.com) ---
Okay, thanks for explanation.
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2020-05-13 2:45 [Bug 207711] New: xfs: data race on ctx->space_used in xlog_cil_insert_items() bugzilla-daemon
2020-05-13 4:07 ` Dave Chinner
2020-05-13 4:07 ` [Bug 207711] " bugzilla-daemon
2020-05-13 8:00 ` bugzilla-daemon
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