From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f69.google.com (mail-oi0-f69.google.com [209.85.218.69]) by kanga.kvack.org (Postfix) with ESMTP id 823656B0033 for ; Mon, 6 Feb 2017 22:25:25 -0500 (EST) Received: by mail-oi0-f69.google.com with SMTP id w144so97637072oiw.0 for ; Mon, 06 Feb 2017 19:25:25 -0800 (PST) Received: from szxga01-in.huawei.com (szxga01-in.huawei.com. [58.251.152.64]) by mx.google.com with ESMTPS id e82si1070650oib.65.2017.02.06.19.25.23 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 06 Feb 2017 19:25:24 -0800 (PST) Subject: Re: [PATCH] mm: extend zero pages to same element pages for zram References: <1483692145-75357-1-git-send-email-zhouxianrong@huawei.com> <1486111347-112972-1-git-send-email-zhouxianrong@huawei.com> <20170205142100.GA9611@bbox> <2f6e188c-5358-eeab-44ab-7634014af651@huawei.com> <20170206234805.GA12188@bbox> <20170207025426.GA1528@bbox> From: zhouxianrong Message-ID: Date: Tue, 7 Feb 2017 11:24:40 +0800 MIME-Version: 1.0 In-Reply-To: <20170207025426.GA1528@bbox> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, sergey.senozhatsky@gmail.com, willy@infradead.org, iamjoonsoo.kim@lge.com, ngupta@vflare.org, Mi.Sophia.Wang@huawei.com, zhouxiyu@huawei.com, weidu.du@huawei.com, zhangshiming5@huawei.com, won.ho.park@huawei.com On 2017/2/7 10:54, Minchan Kim wrote: > On Tue, Feb 07, 2017 at 10:20:57AM +0800, zhouxianrong wrote: > > < snip > > >>>> 3. the below should be modified. >>>> >>>> static inline bool zram_meta_get(struct zram *zram) >>>> @@ -495,11 +553,17 @@ static void zram_meta_free(struct zram_meta *meta, u64 disksize) >>>> >>>> /* Free all pages that are still in this zram device */ >>>> for (index = 0; index < num_pages; index++) { >>>> - unsigned long handle = meta->table[index].handle; >>>> + unsigned long handle; >>>> + >>>> + bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); >>>> + handle = meta->table[index].handle; >>>> >>>> - if (!handle) >>>> + if (!handle || zram_test_flag(meta, index, ZRAM_SAME)) { >>>> + bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); >>>> continue; >>>> + } >>>> >>>> + bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); >>>> zs_free(meta->mem_pool, handle); >>> >>> Could you explain why we need this modification? >>> >>>> } >>>> >>>> @@ -511,7 +575,7 @@ static void zram_meta_free(struct zram_meta *meta, u64 disksize) >>>> static struct zram_meta *zram_meta_alloc(char *pool_name, u64 disksize) >>>> { >>>> size_t num_pages; >>>> - struct zram_meta *meta = kmalloc(sizeof(*meta), GFP_KERNEL); >>>> + struct zram_meta *meta = kzalloc(sizeof(*meta), GFP_KERNEL); >>> >>> Ditto >>> >>>> >>>> >>> >>> . >>> >> >> because of union of handle and element, i think a non-zero element (other than handle) is prevented from freeing. >> if zram_meta_get was modified, zram_meta_alloc did so. > > Right. Thanks but I don't see why we need the locking in there and modification of > zram_meta_alloc. > > Isn't it enough with this? i am afraid someone do reset_store, so did lock. yes, i am wrong, zram_meta_alloc should not be modified here. because meta->table has already cleared meta->table = vzalloc(num_pages * sizeof(*meta->table)); > > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c > index c20b05a84f21..a25d34a8af19 100644 > --- a/drivers/block/zram/zram_drv.c > +++ b/drivers/block/zram/zram_drv.c > @@ -425,8 +425,11 @@ static void zram_meta_free(struct zram_meta *meta, u64 disksize) > /* Free all pages that are still in this zram device */ > for (index = 0; index < num_pages; index++) { > unsigned long handle = meta->table[index].handle; > - > - if (!handle) > + /* > + * No memory is allocated for same element filled pages. > + * Simply clear same page flag. > + */ > + if (!handle || zram_test_flag(meta, index, ZRAM_SAME)) > continue; > > zs_free(meta->mem_pool, handle); > > . > -- 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