* FAILED: patch "[PATCH] io_uring: dont kill fasync under completion_lock" failed to apply to 5.10-stable tree
@ 2021-01-15 10:49 gregkh
0 siblings, 0 replies; 2+ messages in thread
From: gregkh @ 2021-01-15 10:49 UTC (permalink / raw)
To: asml.silence, axboe; +Cc: stable
The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 4aa84f2ffa81f71e15e5cffc2cc6090dbee78f8e Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <asml.silence@gmail.com>
Date: Thu, 7 Jan 2021 03:15:42 +0000
Subject: [PATCH] io_uring: dont kill fasync under completion_lock
CPU0 CPU1
---- ----
lock(&new->fa_lock);
local_irq_disable();
lock(&ctx->completion_lock);
lock(&new->fa_lock);
<Interrupt>
lock(&ctx->completion_lock);
*** DEADLOCK ***
Move kill_fasync() out of io_commit_cqring() to io_cqring_ev_posted(),
so it doesn't hold completion_lock while doing it. That saves from the
reported deadlock, and it's just nice to shorten the locking time and
untangle nested locks (compl_lock -> wq_head::lock).
Reported-by: syzbot+91ca3f25bd7f795f019c@syzkaller.appspotmail.com
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 91e517ad1421..401316fe2ae2 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1345,11 +1345,6 @@ static void __io_commit_cqring(struct io_ring_ctx *ctx)
/* order cqe stores with ring update */
smp_store_release(&rings->cq.tail, ctx->cached_cq_tail);
-
- if (wq_has_sleeper(&ctx->cq_wait)) {
- wake_up_interruptible(&ctx->cq_wait);
- kill_fasync(&ctx->cq_fasync, SIGIO, POLL_IN);
- }
}
static void io_put_identity(struct io_uring_task *tctx, struct io_kiocb *req)
@@ -1711,6 +1706,10 @@ static void io_cqring_ev_posted(struct io_ring_ctx *ctx)
wake_up(&ctx->sq_data->wait);
if (io_should_trigger_evfd(ctx))
eventfd_signal(ctx->cq_ev_fd, 1);
+ if (wq_has_sleeper(&ctx->cq_wait)) {
+ wake_up_interruptible(&ctx->cq_wait);
+ kill_fasync(&ctx->cq_fasync, SIGIO, POLL_IN);
+ }
}
static void io_cqring_ev_posted_iopoll(struct io_ring_ctx *ctx)
@@ -1721,6 +1720,10 @@ static void io_cqring_ev_posted_iopoll(struct io_ring_ctx *ctx)
}
if (io_should_trigger_evfd(ctx))
eventfd_signal(ctx->cq_ev_fd, 1);
+ if (wq_has_sleeper(&ctx->cq_wait)) {
+ wake_up_interruptible(&ctx->cq_wait);
+ kill_fasync(&ctx->cq_fasync, SIGIO, POLL_IN);
+ }
}
/* Returns true if there are no backlogged entries after the flush */
^ permalink raw reply related [flat|nested] 2+ messages in thread
* FAILED: patch "[PATCH] io_uring: dont kill fasync under completion_lock" failed to apply to 5.10-stable tree
@ 2021-01-11 11:44 gregkh
0 siblings, 0 replies; 2+ messages in thread
From: gregkh @ 2021-01-11 11:44 UTC (permalink / raw)
To: asml.silence, axboe; +Cc: stable
The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 4aa84f2ffa81f71e15e5cffc2cc6090dbee78f8e Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <asml.silence@gmail.com>
Date: Thu, 7 Jan 2021 03:15:42 +0000
Subject: [PATCH] io_uring: dont kill fasync under completion_lock
CPU0 CPU1
---- ----
lock(&new->fa_lock);
local_irq_disable();
lock(&ctx->completion_lock);
lock(&new->fa_lock);
<Interrupt>
lock(&ctx->completion_lock);
*** DEADLOCK ***
Move kill_fasync() out of io_commit_cqring() to io_cqring_ev_posted(),
so it doesn't hold completion_lock while doing it. That saves from the
reported deadlock, and it's just nice to shorten the locking time and
untangle nested locks (compl_lock -> wq_head::lock).
Reported-by: syzbot+91ca3f25bd7f795f019c@syzkaller.appspotmail.com
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 91e517ad1421..401316fe2ae2 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1345,11 +1345,6 @@ static void __io_commit_cqring(struct io_ring_ctx *ctx)
/* order cqe stores with ring update */
smp_store_release(&rings->cq.tail, ctx->cached_cq_tail);
-
- if (wq_has_sleeper(&ctx->cq_wait)) {
- wake_up_interruptible(&ctx->cq_wait);
- kill_fasync(&ctx->cq_fasync, SIGIO, POLL_IN);
- }
}
static void io_put_identity(struct io_uring_task *tctx, struct io_kiocb *req)
@@ -1711,6 +1706,10 @@ static void io_cqring_ev_posted(struct io_ring_ctx *ctx)
wake_up(&ctx->sq_data->wait);
if (io_should_trigger_evfd(ctx))
eventfd_signal(ctx->cq_ev_fd, 1);
+ if (wq_has_sleeper(&ctx->cq_wait)) {
+ wake_up_interruptible(&ctx->cq_wait);
+ kill_fasync(&ctx->cq_fasync, SIGIO, POLL_IN);
+ }
}
static void io_cqring_ev_posted_iopoll(struct io_ring_ctx *ctx)
@@ -1721,6 +1720,10 @@ static void io_cqring_ev_posted_iopoll(struct io_ring_ctx *ctx)
}
if (io_should_trigger_evfd(ctx))
eventfd_signal(ctx->cq_ev_fd, 1);
+ if (wq_has_sleeper(&ctx->cq_wait)) {
+ wake_up_interruptible(&ctx->cq_wait);
+ kill_fasync(&ctx->cq_fasync, SIGIO, POLL_IN);
+ }
}
/* Returns true if there are no backlogged entries after the flush */
^ permalink raw reply related [flat|nested] 2+ messages in thread
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2021-01-11 11:44 gregkh
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