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From: Pavel Begunkov <[email protected]>
To: Jens Axboe <[email protected]>,
	[email protected], [email protected]
Subject: [PATCH 1/1] io_uring: fix refcounting with OOM
Date: Sat, 25 Jan 2020 11:59:30 +0300	[thread overview]
Message-ID: <fa69cae513308ef3f681e13888a4f551c67ef3a2.1579942715.git.asml.silence@gmail.com> (raw)

In case of out of memory the second argument of percpu_ref_put_many() in
io_submit_sqes() may evaluate into "nr - (-EAGAIN)", that is clearly
wrong.

Fixes: 2b85edfc0c90 ("io_uring: batch getting pcpu references")
Signed-off-by: Pavel Begunkov <[email protected]>
---
 fs/io_uring.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index a4b496815783..744e8a90b543 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -4912,8 +4912,11 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
 			break;
 	}
 
-	if (submitted != nr)
-		percpu_ref_put_many(&ctx->refs, nr - submitted);
+	if (unlikely(submitted != nr)) {
+		int ref_used = (submitted == -EAGAIN) ? 0 : submitted;
+
+		percpu_ref_put_many(&ctx->refs, nr - ref_used);
+	}
 
 	io_submit_end(ctx);
 	if (nr > IO_PLUG_THRESHOLD)
-- 
2.24.0


             reply	other threads:[~2020-01-25  9:00 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-25  8:59 Pavel Begunkov [this message]
2020-01-25 16:46 ` [PATCH 1/1] io_uring: fix refcounting with OOM Jens Axboe
2020-01-25 19:27   ` Pavel Begunkov
2020-01-25 19:34 ` [PATCH v2] " Pavel Begunkov

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