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From: Pavel Begunkov <asml.silence@gmail.com>
To: Jens Axboe <axboe@kernel.dk>,
	io-uring@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v2] io_uring: fix refcounting with OOM
Date: Sat, 25 Jan 2020 22:34:01 +0300	[thread overview]
Message-ID: <17022002efedf99758627055901c94d9fa344ec9.1579980745.git.asml.silence@gmail.com> (raw)
In-Reply-To: <fa69cae513308ef3f681e13888a4f551c67ef3a2.1579942715.git.asml.silence@gmail.com>

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 <asml.silence@gmail.com>
---

v2: rebase

 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 25f29ef81698..e79d6e47dc7b 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -4896,8 +4896,11 @@ 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);
+	}
 	if (link)
 		io_queue_link_head(link);
 	if (statep)
-- 
2.24.0


      parent reply	other threads:[~2020-01-25 19:34 UTC|newest]

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

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