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imf08.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b="SDXK/0wx"; spf=pass (imf08.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1783686131; b=JTDf7/a0CTQq1LWIwBx4MSGLCeSCJPqpDGDKp4+KNeqLGpoAvlII+yqDIjXE09Co2FHBMJ w+sZ8G5UF1lMNphXh39sJIE7ZgPhUY3rxG1hqsniCTkErguf94b6GcJwK8j0Y/0rIzSswN 97I5Qf1sdRNdcGr34NqG2jz135464FM= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 98662405D2; Fri, 10 Jul 2026 12:22:10 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A0DAE1F0155A; Fri, 10 Jul 2026 12:22:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783686130; bh=fDgjRBlYu1xxBnZ1IMeHj51O6m+GeaRvDabt0r9az68=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=SDXK/0wxM+vVK5Aq9AxQaVGqL3/lAKIHy1sJwPtT4QLKGiyAwSKhXKd1G9DrHgsas ve4xSKX2z1MWh9cMllqIqSzkrxvJLiPfr34a5Zu9v0ERWAMykx6UVg6eDHjivhqESK NmGg9NMzLOVemntDlyZHzhB6warnBuU0ZHNV3ruxdMudK2Q2MGFxf6060nUEAFY1zB DbwRHu6rgoHVw3DWF2XoJ0X7jS+QnF16R7uZwjvzhUaWC7ENs0qyKmS6UL/XrSgLXX j8UfhpgN4jmgZeUuVMkQIFyfonnp/Hi0Oh1c8xJkhH+GTtP8IpnQ+U8tlQWkCj4ItL vqEeSka/ysxiQ== Message-ID: <87b94730-7543-487e-8f3e-c13251a00a21@kernel.org> Date: Fri, 10 Jul 2026 14:22:05 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/5] mm/rmap: convert page -> folio for hwpoison checks To: Dev Jain , akpm@linux-foundation.org, ljs@kernel.org, muchun.song@linux.dev, osalvador@suse.de Cc: riel@surriel.com, liam@infradead.org, vbabka@kernel.org, harry@kernel.org, jannh@google.com, lance.yang@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, ryan.roberts@arm.com, anshuman.khandual@arm.com References: <20260710055915.638659-1-dev.jain@arm.com> <20260710055915.638659-2-dev.jain@arm.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 6C95F160006 X-Stat-Signature: r1nwzby4iixj86gihiew4fi1pbjkikh6 X-HE-Tag: 1783686131-119817 X-HE-Meta: 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 6a6VHEBs JZAI2vHP9kZpsQNkoRa8RX2DPr1B6dPLYRS/HZ0ZuFqvDyYeLMEcm2qZh9/LhW10EFzlN/4ZxchKqlgIbKRr00lrkfDiRz3JTqkioXN1AYTfpLpEeuZpTrI1lrpvlYNCch6rYe+3nLprOvc0CqwGBA1t4K1lFTtvZj/q9txYVLI8Hw5Km7R3lNVxP5tJRckmlZ5hppcyU8Ss3mi0m5es7ZMaXvSpS1qMMnnwNvI5LUoJz0LODQil7zdazX0cHRQx2nT9VqW0eKod461M5RUSHspmunoTVXTwpFG3ibiKCYYrg8ijx7+NDqWdRoaHRbKlUFTkAWUQk8ZpOFZFdCTvJwTq1JA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/10/26 07:59, Dev Jain wrote: > try_to_unmap() receives hugetlb folios only from the hwpoison path. > hugetlb_update_hwpoison() sets the hugetlb folio's head-page > hwpoison bit, and page_vma_mapped_walk() reports the hugetlb mapping at > the head PFN, so the previous PageHWPoison(subpage) check happened to > work for hugetlb. > > For non-hugetlb folios, unmap_poisoned_folio() currently rejects large > folios before calling try_to_unmap(). Hence it is always the case that > if try_to_unmap_one() handles an hwpoisoned folio, then the head page is > marked with the poison bit. > > Therefore, convert the poisoned subpage checks to folio_test_hwpoison(). > > No functional change intended, except that, while at it, > convert VM_BUG_* to VM_WARN_*. > > Acked-by: David Hildenbrand (Arm) > Signed-off-by: Dev Jain > --- > mm/rmap.c | 13 +++++++++---- > 1 file changed, 9 insertions(+), 4 deletions(-) > > diff --git a/mm/rmap.c b/mm/rmap.c > index 9939400e77c79..dbb077f8443e3 100644 > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -2122,10 +2122,11 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, > bool anon = folio_test_anon(folio); > > /* > - * The try_to_unmap() is only passed a hugetlb page > - * in the case where the hugetlb page is poisoned. > + * The try_to_unmap() is only passed a hugetlb folio > + * in the case where the hugetlb folio contains a > + * poisoned page. > */ > - VM_BUG_ON_PAGE(!PageHWPoison(subpage), subpage); > + VM_WARN_ON_FOLIO(!folio_test_hwpoison(folio), folio); > /* > * huge_pmd_unshare may unmap an entire PMD page. > * There is no way of knowing exactly which PMDs may > @@ -2204,7 +2205,11 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, > /* Update high watermark before we lower rss */ > update_hiwater_rss(mm); > > - if (PageHWPoison(subpage) && (flags & TTU_HWPOISON)) { > + /* > + * With TTU_HWPOISON, we only expect small folios or hugetlb > + * folios here for now. > + */ Is this comment helpful given that you change that in patch #2, where you forget to update the comment? :) -- Cheers, David