linux-kernel - Re: [PATCH mm-new v2 2/3] mm/khugepaged: use VM_WARN_ON_FOLIO instead of VM_BUG_ON

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Message-ID: <20251007003539.evunghgqxysojtr2@master>
Date: Tue, 7 Oct 2025 00:35:39 +0000
From: Wei Yang <richard.weiyang@...il.com>
To: Lance Yang <lance.yang@...ux.dev>
Cc: akpm@...ux-foundation.org, david@...hat.com, lorenzo.stoakes@...cle.com,
	ziy@...dia.com, baolin.wang@...ux.alibaba.com,
	Liam.Howlett@...cle.com, npache@...hat.com, ryan.roberts@....com,
	dev.jain@....com, baohua@...nel.org, ioworker0@...il.com,
	richard.weiyang@...il.com, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [PATCH mm-new v2 2/3] mm/khugepaged: use VM_WARN_ON_FOLIO
 instead of VM_BUG_ON_FOLIO for non-anon folios

On Mon, Oct 06, 2025 at 10:43:37PM +0800, Lance Yang wrote:
>From: Lance Yang <lance.yang@...ux.dev>
>
>As Zi pointed out, we should avoid crashing the kernel for conditions
>that can be handled gracefully. Encountering a non-anonymous folio in an
>anonymous VMA is a bug, but a warning is sufficient.
>
>This patch changes the VM_BUG_ON_FOLIO(!folio_test_anon(folio)) to a
>VM_WARN_ON_FOLIO() in both __collapse_huge_page_isolate() and
>hpage_collapse_scan_pmd(), and then aborts the scan with SCAN_PAGE_ANON.
>
>Making more of the scanning logic common between hpage_collapse_scan_pmd()
>and __collapse_huge_page_isolate(), as suggested by Dev.
>
>Suggested-by: Dev Jain <dev.jain@....com>
>Suggested-by: Zi Yan <ziy@...dia.com>
>Signed-off-by: Lance Yang <lance.yang@...ux.dev>

Reviewed-by: Wei Yang <richard.weiyang@...il.com>

-- 
Wei Yang
Help you, Help me