From: Kiryl Shutsemau <kirill@shutemov.name>
To: Wei Yang <richard.weiyang@gmail.com>
Cc: akpm@linux-foundation.org, david@redhat.com,
lorenzo.stoakes@oracle.com, ziy@nvidia.com,
baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com,
npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com,
baohua@kernel.org, lance.yang@linux.dev, xu.xin16@zte.com.cn,
chengming.zhou@linux.dev, linux-mm@kvack.org,
Dan Carpenter <dan.carpenter@linaro.org>
Subject: Re: [Patch v4 1/2] mm/ksm: don't call mm_slot_entry() when the slot is NULL
Date: Mon, 29 Sep 2025 11:58:01 +0100 [thread overview]
Message-ID: <fkxkvkapvckqp366untyvwp4fpnl6ljdegfxteqniil6427flz@36ace6twyslf> (raw)
In-Reply-To: <20250927004539.19308-2-richard.weiyang@gmail.com>
On Sat, Sep 27, 2025 at 12:45:38AM +0000, Wei Yang wrote:
> When using mm_slot in ksm, there is code like:
>
> slot = mm_slot_lookup(mm_slots_hash, mm);
> mm_slot = mm_slot_entry(slot, struct ksm_mm_slot, slot);
> if (mm_slot && ..) {
> }
>
> The mm_slot_entry() won't return a valid value if slot is NULL generally.
> But currently it works since slot is the first element of struct
> ksm_mm_slot.
>
> To reduce the ambiguity and make it robust, only call mm_slot_entry()
> when we have a valid slot.
>
> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Dev Jain <dev.jain@arm.com>
> Cc: Lance Yang <lance.yang@linux.dev>
> Cc: Kiryl Shutsemau <kirill@shutemov.name>
> Cc: xu xin <xu.xin16@zte.com.cn>
> Cc: Dan Carpenter <dan.carpenter@linaro.org>
> Cc: Chengming Zhou <chengming.zhou@linux.dev>
Acked-by: Kiryl Shutsemau <kas@kernel.org>
--
Kiryl Shutsemau / Kirill A. Shutemov
next prev parent reply other threads:[~2025-09-29 10:58 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-27 0:45 [Patch v4 0/2] mm_slot: fix the usage of mm_slot_entry() Wei Yang
2025-09-27 0:45 ` [Patch v4 1/2] mm/ksm: don't call mm_slot_entry() when the slot is NULL Wei Yang
2025-09-27 8:39 ` Muhammad Usama Anjum
2025-09-28 13:53 ` Dev Jain
2025-09-29 8:13 ` David Hildenbrand
2025-09-29 10:58 ` Kiryl Shutsemau [this message]
2025-09-29 15:14 ` Zi Yan
2025-09-27 0:45 ` [Patch v4 2/2] mm/khugepaged: remove definition of struct khugepaged_mm_slot Wei Yang
2025-09-27 8:40 ` Muhammad Usama Anjum
2025-09-29 8:13 ` David Hildenbrand
2025-09-29 15:16 ` Zi Yan
2025-09-30 6:01 ` Raghavendra K T
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