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linux/io_uring
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Jens Axboe 3a84fa7847 io_uring/tctx: work around xa_store() allocation error issue 
commit 7eb75ce752 upstream.

syzbot triggered the following WARN_ON:

WARNING: CPU: 0 PID: 16 at io_uring/tctx.c:51 __io_uring_free+0xfa/0x140 io_uring/tctx.c:51

which is the

WARN_ON_ONCE(!xa_empty(&tctx->xa));

sanity check in __io_uring_free() when a io_uring_task is going through
its final put. The syzbot test case includes injecting memory allocation
failures, and it very much looks like xa_store() can fail one of its
memory allocations and end up with ->head being non-NULL even though no
entries exist in the xarray.

Until this issue gets sorted out, work around it by attempting to
iterate entries in our xarray, and WARN_ON_ONCE() if one is found.

Reported-by: syzbot+cc36d44ec9f368e443d3@syzkaller.appspotmail.com
Link: https://lore.kernel.org/io-uring/673c1643.050a0220.87769.0066.GAE@google.com/
Signed-off-by: Jens Axboe <axboe@kernel.dk>
[ Modify the function in io_uring.c because it's located here in v5.15. ]
Signed-off-by: Robert Garcia <rob_garcia@163.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2026-04-18 10:33:35 +02:00
..
io-wq.c io_uring/io-wq: check IO_WQ_BIT_EXIT inside work run loop 2026-04-18 10:33:17 +02:00
io-wq.h io_uring: break out of iowq iopoll on teardown 2023-09-19 12:22:54 +02:00
io_uring.c io_uring/tctx: work around xa_store() allocation error issue 2026-04-18 10:33:35 +02:00
Makefile io_uring: move to separate directory 2022-12-14 11:37:31 +01:00