public inbox for [email protected]
 help / color / mirror / Atom feed
* [PATCH] io_uring: account user memory freed when exit has been queued
@ 2020-07-10 15:16 Jens Axboe
  0 siblings, 0 replies; only message in thread
From: Jens Axboe @ 2020-07-10 15:16 UTC (permalink / raw)
  To: io-uring

We currently account the memory after the exit work has been run, but
that leaves a gap where a process has closed its ring and until the
memory has been accounted as freed. If the memlocked ulimit is
borderline, then that can introduce spurious setup errors returning
-ENOMEM because the free work hasn't been run yet.

Account this as freed when we close the ring, as not to expose a tiny
gap where setting up a new ring can fail.

Signed-off-by: Jens Axboe <[email protected]>

---

diff --git a/fs/io_uring.c b/fs/io_uring.c
index fc07baf4392a..ca8abde48b6c 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -7351,9 +7351,6 @@ static void io_ring_ctx_free(struct io_ring_ctx *ctx)
 	io_mem_free(ctx->sq_sqes);
 
 	percpu_ref_exit(&ctx->refs);
-	if (ctx->account_mem)
-		io_unaccount_mem(ctx->user,
-				ring_pages(ctx->sq_entries, ctx->cq_entries));
 	free_uid(ctx->user);
 	put_cred(ctx->creds);
 	kfree(ctx->cancel_hash);
@@ -7438,6 +7435,16 @@ static void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx)
 	if (ctx->rings)
 		io_cqring_overflow_flush(ctx, true);
 	idr_for_each(&ctx->personality_idr, io_remove_personalities, ctx);
+
+	/*
+	 * Do this upfront, so we won't have a grace period where the ring
+	 * is closed but resources aren't reaped yet. This can cause
+	 * spurious failure in setting up a new ring.
+	 */
+	if (ctx->account_mem)
+		io_unaccount_mem(ctx->user,
+				ring_pages(ctx->sq_entries, ctx->cq_entries));
+
 	INIT_WORK(&ctx->exit_work, io_ring_exit_work);
 	queue_work(system_wq, &ctx->exit_work);
 }

-- 
Jens Axboe


^ permalink raw reply related	[flat|nested] only message in thread

only message in thread, other threads:[~2020-07-10 15:20 UTC | newest]

Thread overview: (only message) (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2020-07-10 15:16 [PATCH] io_uring: account user memory freed when exit has been queued Jens Axboe

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox