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| author |   Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com> | 2020-05-01 08:52:56 +0800 |
|---|---|---|
| committer |   Jens Axboe <axboe@kernel.dk> | 2020-04-30 22:24:27 -0600 |
| commit | 3fd44c86711f71156b586c22b0495c58f69358bb (patch) | |
| tree | f68fdffa820b90785254cabbebee9c8f0563dbac /fs | |
| parent | io_uring: use proper references for fallback_req locking (diff) | |
| download | wireguard-linux-3fd44c86711f71156b586c22b0495c58f69358bb.tar.xz wireguard-linux-3fd44c86711f71156b586c22b0495c58f69358bb.zip | |
io_uring: use cond_resched() in io_ring_ctx_wait_and_kill()
While working on to make io_uring sqpoll mode support syscalls that need
struct files_struct, I got cpu soft lockup in io_ring_ctx_wait_and_kill(),
while (ctx->sqo_thread && !wq_has_sleeper(&ctx->sqo_wait))
cpu_relax();
above loop never has an chance to exit, it's because preempt isn't enabled
in the kernel, and the context calling io_ring_ctx_wait_and_kill() and
io_sq_thread() run in the same cpu, if io_sq_thread calls a cond_resched()
yield cpu and another context enters above loop, then io_sq_thread() will
always in runqueue and never exit.
Use cond_resched() can fix this issue.
Reported-by: syzbot+66243bb7126c410cefe6@syzkaller.appspotmail.com
Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/io_uring.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index 3da2a02531e6..5ca2da6648d0 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -7343,7 +7343,7 @@ static void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx) * it could cause shutdown to hang. */ while (ctx->sqo_thread && !wq_has_sleeper(&ctx->sqo_wait)) - cpu_relax(); + cond_resched(); io_kill_timeouts(ctx); io_poll_remove_all(ctx); |