From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:45060 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732694AbeGJS2e (ORCPT ); Tue, 10 Jul 2018 14:28:34 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mikulas Patocka , Mike Snitzer Subject: [PATCH 4.4 40/47] dm bufio: drop the lock when doing GFP_NOIO allocation Date: Tue, 10 Jul 2018 20:25:04 +0200 Message-Id: <20180710182338.851964826@linuxfoundation.org> In-Reply-To: <20180710182337.047502999@linuxfoundation.org> References: <20180710182337.047502999@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mikulas Patocka commit 41c73a49df31151f4ff868f28fe4f129f113fa2c upstream. If the first allocation attempt using GFP_NOWAIT fails, drop the lock and retry using GFP_NOIO allocation (lock is dropped because the allocation can take some time). Note that we won't do GFP_NOIO allocation when we loop for the second time, because the lock shouldn't be dropped between __wait_for_free_buffer and __get_unclaimed_buffer. Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman --- drivers/md/dm-bufio.c | 10 ++++++++++ 1 file changed, 10 insertions(+) --- a/drivers/md/dm-bufio.c +++ b/drivers/md/dm-bufio.c @@ -813,6 +813,7 @@ enum new_flag { static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client *c, enum new_flag nf) { struct dm_buffer *b; + bool tried_noio_alloc = false; /* * dm-bufio is resistant to allocation failures (it just keeps @@ -837,6 +838,15 @@ static struct dm_buffer *__alloc_buffer_ if (nf == NF_PREFETCH) return NULL; + if (dm_bufio_cache_size_latch != 1 && !tried_noio_alloc) { + dm_bufio_unlock(c); + b = alloc_buffer(c, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); + dm_bufio_lock(c); + if (b) + return b; + tried_noio_alloc = true; + } + if (!list_empty(&c->reserved_buffers)) { b = list_entry(c->reserved_buffers.next, struct dm_buffer, lru_list);