linux-kernel - Re: [PATCH 1/2] mm/zswap: don't return LRU

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <76b9e52a-9b51-4e4d-93ca-24a5aa3c4dca@linux.dev>
Date: Sat, 27 Jan 2024 22:33:49 +0800
From: Chengming Zhou <chengming.zhou@...ux.dev>
To: Johannes Weiner <hannes@...xchg.org>
Cc: yosryahmed@...gle.com, nphamcs@...il.com, akpm@...ux-foundation.org,
 linux-mm@...ck.org, linux-kernel@...r.kernel.org,
 Chengming Zhou <zhouchengming@...edance.com>
Subject: Re: [PATCH 1/2] mm/zswap: don't return LRU_SKIP if we have dropped
 lru lock

On 2024/1/26 22:28, Johannes Weiner wrote:
> On Fri, Jan 26, 2024 at 08:30:14AM +0000, chengming.zhou@...ux.dev wrote:
>> From: Chengming Zhou <zhouchengming@...edance.com>
>>
>> LRU_SKIP can only be returned if we don't ever dropped lru lock, or
>> we need to return LRU_RETRY to restart from the head of lru list.
> 
> Good catch. Can you mention the possible consequences in the log?
> 
> "Otherwise, the iteration might continue from a cursor position that
> was freed while the locks were dropped."?

Good, will do.

> 
>> Actually we may need to introduce another LRU_STOP to really terminate
>> the ongoing shrinking scan process, when we encounter a warm page
>> already in the swap cache. The current list_lru implementation
>> doesn't have this function to early break from __list_lru_walk_one.
>>
>> Fixes: b5ba474f3f51 ("zswap: shrink zswap pool based on memory pressure")
>> Signed-off-by: Chengming Zhou <zhouchengming@...edance.com>
> 
> Acked-by: Johannes Weiner <hannes@...xchg.org>

Thanks.