From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 6FAB018BC3D for ; Fri, 10 Jul 2026 13:14:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783689282; cv=none; b=iTqyVSuCcdFFwlcJ4FHSDcDqmjENNRSHgTHq1PTbO4U5VjkIuKZKDlugNebt+NcG1kYTpdNpK4vJOZ5y6vzUkSXKOFaYTCFVScDfCevQ9CG4MSG1xUR5rnJtGjSEkiUF4CRNpbZynPDN94xZNhLdiusAZq6dpuuAxcduBL+fjwY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783689282; c=relaxed/simple; bh=dyNdfZwM1MyPcYXLpv3sx3GNF4QSc6vm5iBHxl3+7lg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=JnnTjYBqLdy1CPXHB1UHd6xUDN5o362dum9igqZAPG0MZf5FcY2Jer8xYc11KsIuJqrvTxmR8dmfxZiSke+d3xFKLADn1WOLdZp+i+7oNR95XVjOhvEIUcGTdoHYRFnHWY5Y8EwXqJTgcbi0o732lH2lX6Laql9f0ZJ2gEHREgM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=LJPj6Vqb; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="LJPj6Vqb" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 34869176A; Fri, 10 Jul 2026 06:14:35 -0700 (PDT) Received: from [10.164.19.51] (unknown [10.164.19.51]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A57013F66F; Fri, 10 Jul 2026 06:14:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1783689279; bh=dyNdfZwM1MyPcYXLpv3sx3GNF4QSc6vm5iBHxl3+7lg=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=LJPj6Vqbkc3mTMUAI93C8NbOwBloaliXm1yDvo2pCycXonU39JnmEbEGvRotUsJQs v3buCtsFQPWzwqGa6zUBfB8e5rsaJp3KNo8qcyHZBphFbqSqYPaG89oDANyNyHz3ci AfbaYh0DMEzBATMahNiSDoLVM90p3NKgu7nNs2/Y= Message-ID: Date: Fri, 10 Jul 2026 18:44:32 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/5] mm/rmap: convert page -> folio for hwpoison checks To: "David Hildenbrand (Arm)" , 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> <87b94730-7543-487e-8f3e-c13251a00a21@kernel.org> Content-Language: en-US From: Dev Jain In-Reply-To: <87b94730-7543-487e-8f3e-c13251a00a21@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/07/26 5:52 pm, David Hildenbrand (Arm) wrote: > 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? :) Nice spot, let me update this comment in patch 2. >