From: Chengming Zhou <chengming.zhou@linux.dev>
To: Sergey Senozhatsky <senozhatsky@chromium.org>,
Chengming Zhou <zhouchengming@bytedance.com>
Cc: yosryahmed@google.com, hannes@cmpxchg.org, nphamcs@gmail.com,
Andrew Morton <akpm@linux-foundation.org>,
Minchan Kim <minchan@kernel.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 1/2] mm/zsmalloc: don't hold locks of all pages when free_zspage()
Date: Wed, 28 Feb 2024 13:14:48 +0800 [thread overview]
Message-ID: <5a556476-05b2-483e-8875-eeb3e2a51151@linux.dev> (raw)
In-Reply-To: <20240228043358.GF11972@google.com>
On 2024/2/28 12:33, Sergey Senozhatsky wrote:
> On (24/02/27 03:02), Chengming Zhou wrote:
> [..]
>> @@ -978,10 +974,11 @@ static struct zspage *alloc_zspage(struct zs_pool *pool,
>> pages[i] = page;
>> }
>>
>> - create_page_chain(class, zspage, pages);
>> init_zspage(class, zspage);
>> zspage->pool = pool;
>> zspage->class = class->index;
>> + /* RCU set_zspage() after zspage initialized. */
>> + create_page_chain(class, zspage, pages);
>
> So this hasn't been tested, has it?
I have tested it in my test vm, but it hasn't KASAN enabled. I tested the
kernel build in tmpfs with zswap enabled using zsmalloc pool, not sure
why the kernel didn't crash then...
>
> init_zspage() does not like to be invoked before create_page_chain(),
> because we haven't setup required pointers yet.
You're right, I can reproduce the problem with KASAN enabled this time,
create_page_chain() should be put before init_zspage(), which will iterate
over the pages to create free objects list.
>
> So when init_zspage() calls get_first_page() it gets NULL zspage->first_page
> which we then use in is_first_page(first_page)->PagePrivate(page). As far as
> I can tell.
Thanks! I will fix it and test throughly before send an update.
next prev parent reply other threads:[~2024-02-28 5:15 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-27 3:02 [PATCH 0/2] mm/zsmalloc: simplify synchronization between zs_page_migrate() and free_zspage() Chengming Zhou
2024-02-27 3:02 ` [PATCH 1/2] mm/zsmalloc: don't hold locks of all pages when free_zspage() Chengming Zhou
2024-02-28 4:33 ` Sergey Senozhatsky
2024-02-28 5:14 ` Chengming Zhou [this message]
2024-02-28 5:29 ` Sergey Senozhatsky
2024-02-28 5:42 ` Chengming Zhou
2024-02-28 6:07 ` Sergey Senozhatsky
2024-02-28 6:01 ` Sergey Senozhatsky
2024-02-28 6:44 ` Chengming Zhou
2024-02-28 6:14 ` Sergey Senozhatsky
2024-02-28 6:49 ` Chengming Zhou
2024-02-27 3:02 ` [PATCH 2/2] mm/zsmalloc: remove the deferred free mechanism Chengming Zhou
2024-02-28 1:57 ` [PATCH 0/2] mm/zsmalloc: simplify synchronization between zs_page_migrate() and free_zspage() Sergey Senozhatsky
2024-02-28 2:22 ` [External] " Chengming Zhou
2024-02-28 3:54 ` Sergey Senozhatsky
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