From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f54.google.com (mail-pa0-f54.google.com [209.85.220.54]) by kanga.kvack.org (Postfix) with ESMTP id 8AB596B0032 for ; Wed, 21 Jan 2015 09:21:20 -0500 (EST) Received: by mail-pa0-f54.google.com with SMTP id eu11so18776985pac.13 for ; Wed, 21 Jan 2015 06:21:20 -0800 (PST) Received: from mail-pd0-x236.google.com (mail-pd0-x236.google.com. [2607:f8b0:400e:c02::236]) by mx.google.com with ESMTPS id g8si3900717pdk.182.2015.01.21.06.21.18 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 21 Jan 2015 06:21:19 -0800 (PST) Received: by mail-pd0-f182.google.com with SMTP id z10so10600972pdj.13 for ; Wed, 21 Jan 2015 06:21:18 -0800 (PST) Date: Wed, 21 Jan 2015 23:21:53 +0900 From: Sergey Senozhatsky Subject: Re: [PATCH v1 01/10] zram: avoid calling of zram_meta_free under init_lock Message-ID: <20150121142115.GA986@swordfish> References: <1421820866-26521-1-git-send-email-minchan@kernel.org> <1421820866-26521-2-git-send-email-minchan@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1421820866-26521-2-git-send-email-minchan@kernel.org> Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Dan Streetman , Seth Jennings , Nitin Gupta , Juneho Choi , Gunho Lee , Luigi Semenzato , Jerome Marchand , Sergey Senozhatsky On (01/21/15 15:14), Minchan Kim wrote: > We don't need to call zram_meta_free under init_lock. > What we need to prevent race is setting NULL into zram->meta > (ie, init_done). This patch does it. > > Signed-off-by: Minchan Kim > --- > drivers/block/zram/zram_drv.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c > index 9250b3f..7e03d86 100644 > --- a/drivers/block/zram/zram_drv.c > +++ b/drivers/block/zram/zram_drv.c > @@ -719,6 +719,8 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity) > } > > meta = zram->meta; > + zram->meta = NULL; > + > /* Free all pages that are still in this zram device */ > for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) { > unsigned long handle = meta->table[index].handle; > @@ -731,8 +733,6 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity) > zcomp_destroy(zram->comp); > zram->max_comp_streams = 1; > > - zram_meta_free(zram->meta); > - zram->meta = NULL; > /* Reset stats */ > memset(&zram->stats, 0, sizeof(zram->stats)); > > @@ -741,6 +741,7 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity) > set_capacity(zram->disk, 0); > > up_write(&zram->init_lock); > + zram_meta_free(meta); Hello, since we detached ->meta from zram, this one doesn't really need ->init_lock protection: /* Free all pages that are still in this zram device */ for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) { unsigned long handle = meta->table[index].handle; if (!handle) continue; zs_free(meta->mem_pool, handle); } -ss > /* > * Revalidate disk out of the init_lock to avoid lockdep splat. > -- > 1.9.3 > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org