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 C18642E738D for ; Fri, 29 May 2026 09:34:45 +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=1780047286; cv=none; b=EdIIxuYXzC3U109DZByYX17+nPEAfmu54tEcdRKwi1cy+hEPpLw1pFBAIEw0NKamcZYaDPPPNPDRbPj+wHk/IBshc36KOMorKkxdPaqSRoJehRNlm72CXocC7kgmKAtJdyyUnSBkA8oifpLxxO7pVeaF7Ua49ks/kRrIyArM/Uw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780047286; c=relaxed/simple; bh=mhGM0lFSOMg0MxUFevPx9Foz63RVZJD3NUnqKh+hibY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=XyLA0xjODXsl7VRUhnZ4tt1UgT7qPLZUDij3jxp7PNp2FPQl0698t1a0PZ9wDB4e5kEsWuK+K0RWdFYObHHJN/gNeOmIFOMa/4IUsWlZXYCCLHNDhoZT7++eASccsB1lPmekWG7CzmWhXaO6/Za1XfbJbujGq6ROYPBfrOMJCpY= 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=CQDZvE71; 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="CQDZvE71" 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 228F22103; Fri, 29 May 2026 02:34:40 -0700 (PDT) Received: from [10.164.148.36] (unknown [10.164.148.36]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7C9343FB3E; Fri, 29 May 2026 02:34:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1780047285; bh=mhGM0lFSOMg0MxUFevPx9Foz63RVZJD3NUnqKh+hibY=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=CQDZvE71deMPuC3t8Lyx3K6Mnjyv1tsXtezXZ46ta3WtHs48kpR/Rd1mtrDchcVi4 MplYYHqIN+fY0C81LDJ8pSXA2UZ8TvPhdzWdT8S+eXm/D9Rw5POp1zfV8uUOhZDRIA OmBtQEViAPVKlmmZ8P/OdWvEcGumgyHva3P0/2oY= Message-ID: <045afaad-4294-4b59-99f5-6b047e1f26e2@arm.com> Date: Fri, 29 May 2026 15:04:32 +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 03/13] fs/proc: use softleaf_has_pfn() in pagemap PMD walker To: Usama Arif , Andrew Morton , david@kernel.org, chrisl@kernel.org, kasong@tencent.com, ljs@kernel.org, ziy@nvidia.com Cc: bhe@redhat.com, willy@infradead.org, youngjun.park@lge.com, hannes@cmpxchg.org, riel@surriel.com, shakeel.butt@linux.dev, alex@ghiti.fr, kas@kernel.org, baohua@kernel.org, baolin.wang@linux.alibaba.com, npache@redhat.com, Liam.Howlett@oracle.com, ryan.roberts@arm.com, Vlastimil Babka , lance.yang@linux.dev, linux-kernel@vger.kernel.org, nphamcs@gmail.com, shikemeng@huaweicloud.com, kernel-team@meta.com References: <20260427100553.2754667-1-usama.arif@linux.dev> <20260427100553.2754667-4-usama.arif@linux.dev> Content-Language: en-US From: Dev Jain In-Reply-To: <20260427100553.2754667-4-usama.arif@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 27/04/26 3:31 pm, Usama Arif wrote: > pagemap_pmd_range_thp() assumes that every non-present PMD is a > migration entry and unconditionally calls softleaf_to_page(). This > will crash on any non-present PMD type that does not encode a PFN, > such as the upcoming PMD-level swap entries. > > Guard the page lookup with softleaf_has_pfn(), matching how > pte_to_pagemap_entry() already handles non-present PTEs. > > Signed-off-by: Usama Arif > --- > fs/proc/task_mmu.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c > index 751b9ba160fb..6d9f43881e62 100644 > --- a/fs/proc/task_mmu.c > +++ b/fs/proc/task_mmu.c > @@ -2042,8 +2042,8 @@ static int pagemap_pmd_range_thp(pmd_t *pmdp, unsigned long addr, > flags |= PM_SOFT_DIRTY; > if (pmd_swp_uffd_wp(pmd)) > flags |= PM_UFFD_WP; > - VM_WARN_ON_ONCE(!pmd_is_migration_entry(pmd)); I think the existing VM_WARN_ON_ONCE here is wrong. We can indeed reach this path from a non-migration entry. Sending a patch soon. > - page = softleaf_to_page(entry); > + if (softleaf_has_pfn(entry)) > + page = softleaf_to_page(entry); > } > > if (page) {