From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:44712 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030450AbdEWUL4 (ORCPT ); Tue, 23 May 2017 16:11:56 -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 4.11 026/197] dm bufio: check new buffer allocation watermark every 30 seconds Date: Tue, 23 May 2017 22:06:27 +0200 Message-Id: <20170523200823.761515202@linuxfoundation.org> In-Reply-To: <20170523200821.666872592@linuxfoundation.org> References: <20170523200821.666872592@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.11-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mikulas Patocka commit 390020ad2af9ca04844c4f3b1f299ad8746d84c8 upstream. dm-bufio checks a watermark when it allocates a new buffer in __bufio_new(). However, it doesn't check the watermark when the user changes /sys/module/dm_bufio/parameters/max_cache_size_bytes. This may result in a problem - if the watermark is high enough so that all possible buffers are allocated and if the user lowers the value of "max_cache_size_bytes", the watermark will never be checked against the new value because no new buffer would be allocated. To fix this, change __evict_old_buffers() so that it checks the watermark. __evict_old_buffers() is called every 30 seconds, so if the user reduces "max_cache_size_bytes", dm-bufio will react to this change within 30 seconds and decrease memory consumption. Depends-on: 1b0fb5a5b2 ("dm bufio: avoid a possible ABBA deadlock") 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 @@ -1783,9 +1783,17 @@ static void __evict_old_buffers(struct d struct dm_buffer *b, *tmp; unsigned retain_target = get_retain_buffers(c); unsigned count; + LIST_HEAD(write_list); dm_bufio_lock(c); + __check_watermark(c, &write_list); + if (unlikely(!list_empty(&write_list))) { + dm_bufio_unlock(c); + __flush_write_list(&write_list); + dm_bufio_lock(c); + } + count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY]; list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_CLEAN], lru_list) { if (count <= retain_target) @@ -1810,6 +1818,8 @@ static void cleanup_old_buffers(void) mutex_lock(&dm_bufio_clients_lock); + __cache_size_refresh(); + list_for_each_entry(c, &dm_bufio_all_clients, client_list) __evict_old_buffers(c, max_age_hz);