From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753288AbbIXJxI (ORCPT ); Thu, 24 Sep 2015 05:53:08 -0400 Received: from mail-pa0-f54.google.com ([209.85.220.54]:33955 "EHLO mail-pa0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751527AbbIXJxH (ORCPT ); Thu, 24 Sep 2015 05:53:07 -0400 From: Sergey Senozhatsky To: Minchan Kim Cc: Andrew Morton , linux-kernel@vger.kernel.org, Sergey Senozhatsky , Sergey SENOZHATSKY Subject: [PATCH] zram: keep the exact overcommited value in mem_used_max Date: Thu, 24 Sep 2015 18:51:52 +0900 Message-Id: <1443088312-12175-1-git-send-email-sergey.senozhatsky@gmail.com> X-Mailer: git-send-email 2.5.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sergey SENOZHATSKY `mem_used_max' is designed to store the max amount of memory zram consumed to store the data. However, it does not represent the actual 'overcommited' (max) value. The existing code goes to -ENOMEM overcommited case before it updates `->stats.max_used_pages', which hides the reason we went to -ENOMEM in the first place -- we actually used more memory than `->limit_pages': alloced_pages = zs_get_total_pages(meta->mem_pool); if (zram->limit_pages && alloced_pages > zram->limit_pages) { zs_free(meta->mem_pool, handle); ret = -ENOMEM; goto out; } update_used_max(zram, alloced_pages); Which is misleading. User will see -ENOMEM, check `->limit_pages', check `->stats.max_used_pages', which will keep the value BEFORE zram passed `->limit_pages', and see: `->stats.max_used_pages' < `->limit_pages' Move update_used_max() before we do `->limit_pages' check, so that user will see: `->stats.max_used_pages' > `->limit_pages' should the overcommit and -ENOMEM happen. Signed-off-by: Sergey Senozhatsky --- drivers/block/zram/zram_drv.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index cb478ca..6f04fb2 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -738,14 +738,14 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, } alloced_pages = zs_get_total_pages(meta->mem_pool); + update_used_max(zram, alloced_pages); + if (zram->limit_pages && alloced_pages > zram->limit_pages) { zs_free(meta->mem_pool, handle); ret = -ENOMEM; goto out; } - update_used_max(zram, alloced_pages); - cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_WO); if ((clen == PAGE_SIZE) && !is_partial_io(bvec)) { -- 2.5.3