From: Jens Axboe axboe@kernel.dk
commit 309fc03a3284af62eb6082fb60327045a1dabf57 upstream.
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.
Fixes: 85faa7b8346e ("io_uring: punt final io_ring_ctx wait-and-free to workqueue") Cc: stable@vger.kernel.org # v5.7 Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/io_uring.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-)
--- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -7402,9 +7402,6 @@ static void io_ring_ctx_free(struct io_r 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->completions); @@ -7500,6 +7497,16 @@ static void io_ring_ctx_wait_and_kill(st 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); }