linux-kernel - Re: [PATCH] mm/vmscan: Initialize dirty to prevent uninitialized use

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Message-ID: <05b7ed03-60d8-49c2-9094-4f34903f8a64@gmail.com>
Date: Wed, 26 Mar 2025 12:18:28 +0530
From: Purva Yeshi <purvayeshi550@...il.com>
To: Yu Zhao <yuzhao@...gle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/vmscan: Initialize dirty to prevent uninitialized use

On 26/03/25 02:05, Yu Zhao wrote:
> On Tue, Mar 25, 2025 at 1:49 PM Purva Yeshi <purvayeshi550@...il.com> wrote:
>>
>> Fix Smatch-detected error:
>> mm/vmscan.c:3509 walk_pte_range() error: uninitialized symbol 'dirty'.
>> mm/vmscan.c:3522 walk_pte_range() error: uninitialized symbol 'dirty'.
>> mm/vmscan.c:3600 walk_pmd_range_locked() error: uninitialized symbol 'dirty'.
>> mm/vmscan.c:3614 walk_pmd_range_locked() error: uninitialized symbol 'dirty'.
>> mm/vmscan.c:4220 lru_gen_look_around() error: uninitialized symbol 'dirty'.
>> mm/vmscan.c:4232 lru_gen_look_around() error: uninitialized symbol 'dirty'.
>>
>> Smatch reports 'dirty' as uninitialized, leading to potential
>> undefined behavior.
> 
> Thanks -- this seems like false positives from Smatch, where the
> problem should be fixed.

Should we make modifications to address this Smatch error, or is it safe 
to ignore?

> 
>> Explicitly initialize dirty to 0 in walk_pte_range(),
>> walk_pmd_range_locked(), and lru_gen_look_around() in mm/vmscan.c
>> to fix Smatch error.
>>
>> Signed-off-by: Purva Yeshi <purvayeshi550@...il.com>