From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753824AbaHLHhi (ORCPT ); Tue, 12 Aug 2014 03:37:38 -0400 Received: from lgeamrelo04.lge.com ([156.147.1.127]:43167 "EHLO lgeamrelo04.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751831AbaHLHhh (ORCPT ); Tue, 12 Aug 2014 03:37:37 -0400 X-Original-SENDERIP: 10.177.222.156 X-Original-MAILFROM: minchan@kernel.org Date: Tue, 12 Aug 2014 16:37:40 +0900 From: Minchan Kim To: Chao Yu Cc: ngupta@vflare.org, linux-kernel@vger.kernel.org, Jerome Marchand , Sergey Senozhatsky , Andrew Morton Subject: Re: [PATCH] zram: fix incorrectly stat with failed_reads Message-ID: <20140812073740.GA9227@bbox> References: <000001cfb53f$d63b6ea0$82b24be0$@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <000001cfb53f$d63b6ea0$82b24be0$@samsung.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 11, 2014 at 04:39:17PM +0800, Chao Yu wrote: > Since we allocate a temporary buffer in zram_bvec_read to handle partial page > operations in this commit 924bd88d703e53d30f393fac6117f8f1bc79aab6 (Staging: > zram: allow partial page operations), our ->failed_reads value may be incorrect > as we do not increase its value when failed to allocate the temporary buffer. > > Let's fix this issue and correct the annotation of failed_reads. Good catch. Just out of curiosity. Did you catch it by code review or real workload? > > Signed-off-by: Chao Yu > --- > drivers/block/zram/zram_drv.c | 1 + > drivers/block/zram/zram_drv.h | 2 +- > 2 files changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c > index dfa4024..bf8ea1b 100644 > --- a/drivers/block/zram/zram_drv.c > +++ b/drivers/block/zram/zram_drv.c > @@ -413,6 +413,7 @@ static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec, > > if (!uncmem) { > pr_info("Unable to allocate temp memory\n"); > + atomic64_inc(&zram->stats.failed_reads); > ret = -ENOMEM; > goto out_cleanup; > } > diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h > index 5b0afde..e0f725c 100644 > --- a/drivers/block/zram/zram_drv.h > +++ b/drivers/block/zram/zram_drv.h > @@ -84,7 +84,7 @@ struct zram_stats { > atomic64_t compr_data_size; /* compressed size of pages stored */ > atomic64_t num_reads; /* failed + successful */ > atomic64_t num_writes; /* --do-- */ > - atomic64_t failed_reads; /* should NEVER! happen */ > + atomic64_t failed_reads; /* can happen when memory is too low */ > atomic64_t failed_writes; /* can happen when memory is too low */ > atomic64_t invalid_io; /* non-page-aligned I/O requests */ > atomic64_t notify_free; /* no. of swap slot free notifications */ > -- > 2.0.1.474.g72c7794 How abouting moving failed_reads/writes in zram_bvec_rw? int zram_bvec_rw(..) { if (rw == READ) { atomic64_inc(num_reads); ret = zram_bvec_read(xxx); } else { atomic64_inc(&num_writes); ret = zram_bvec_write(xxx); } if (unlikely(ret)) { if (rw == READ) atomic64_inc(failed_reads); else atomic64_inc(failed_writes); } } > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- Kind regards, Minchan Kim