From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A65AD418A5A for ; Thu, 6 Aug 2026 08:36:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786005371; cv=none; b=hZXD5161RcTDFWMLLT4OOQm0Heluukf5pqmhp8XUI/BI5bEP98IEdWUKmxJ47AiWDdGdsKtuhDguE2w5vA+RtWMgmfe5Z9ckODkVI0TSxg4nwDcI/JgmWMtv2BzU/dz4z1SXduDn0v2vEhVFB7gA53Ncr4agIvSPJJIAB0d///w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786005371; c=relaxed/simple; bh=E9UGNIqYV363EHeHrpnvyygwQuZ3Y1RFpuW7mJnNudA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ThVmTHG73Mp0JKAc/6JExpUGsvrCsz76Z5BtvXxkabKWCBXSpWIwy/Y1QHlXPNwlOtNE+xvDTY0rUgYGQwMGikRIQeJu+NAvj2VX6RcB0SxfaNjTYaH9k7be0uPOqz3uI3EJ9x5ORTWV82eSnapXKsl4xeVC4MITMtrU48mEVJk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=kt+UntKS; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="kt+UntKS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 75B051F00A3A; Thu, 6 Aug 2026 08:35:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786005361; bh=+Zf7vT1dgbmGchPNuaWZ7/mC3SH4bQR1pOsfD0HMIQ4=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=kt+UntKS1mKD3CdD5YyzbRET6/9d98rdD+1USoOle7taqWerZrysYUDzu5d9ihTNN A8IFeBs0LRmWngc0ozxr7t5btrhKh6b+qOJ1/k8xqc6Ku9Amo2uIn1HSwO34DjyvmS slnnMdREQasqw9kzSZym8MGP5GIirQvXtAfl2RCy8inUMqzBgmy7SDdeBAqCT7o0a4 ioPuo8wIZ2anVzJUNvoT8pjRKSWdFV6DNzERhOBoFxD+qObcpuB8T4QQNnNsAjCDbx uXI6BDgooGV6+KKFzD0Xe8KtMLrWVg3uyvhvqJgryQVjMyMIIJzFBBLSS4LY7cDAku W87MDlXNktVzA== Message-ID: <1dd77152-bafa-4c4c-a85f-aba054065601@kernel.org> Date: Thu, 6 Aug 2026 10:35:56 +0200 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] mm/ksm: validate KSM rmap items before hwpoison kill To: "Lorenzo Stoakes (ARM)" , Longlong Xia Cc: akpm@linux-foundation.org, xu.xin16@zte.com.cn, chengming.zhou@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, xialonglong@kylinos.cn References: <20260803151151.3472893-1-xialonglong2025@163.com> <20260805162937.1795310-1-xialonglong2025@163.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 >> @@ -3253,9 +3253,13 @@ void collect_procs_ksm(const struct folio *folio, const struct page *page, >> { > > OK so you're literally doing an anon rmap walk here, with the anon lock held. > >> vma = vmac->vma; >> if (vma->vm_mm == t->mm) { >> - addr = rmap_item->address & PAGE_MASK; >> + const unsigned long mapped_addr = >> + page_mapped_in_vma_at_address(page, vma, addr); > > Now you're doing another anon rmap walk? Why on earth are you doing that? And > won't this deadlock? I think it's the same as with page_mapped_in_vma(): it expects the anon vma lock to already haven been taken. At least that's what I understand when looking at collect_procs_anon. :) > > Why aren't you just checking the whether addr is contained in the range here? Yeah, that should be much easier. > > Like: > > /* Make sure VMA wasn't split/remapped */ > if (!in_range(addr, vma->vm_start, vma_pages(vma))) > continue; > > Or something? > >> + >> + if (mapped_addr == -EFAULT) >> + continue; >> add_to_kill_ksm(t, page, vma, to_kill, >> - addr); >> + mapped_addr); >> } >> } >> } >> diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c >> index bac2eb5de63d..f7c5dc9248bc 100644 >> --- a/mm/page_vma_mapped.c >> +++ b/mm/page_vma_mapped.c >> @@ -336,6 +336,26 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw) >> } >> >> #ifdef CONFIG_MEMORY_FAILURE >> +unsigned long page_mapped_in_vma_at_address(const struct page *page, >> + struct vm_area_struct *vma, unsigned long addr) >> +{ >> + struct page_vma_mapped_walk pvmw = { >> + .pfn = page_to_pfn(page), >> + .nr_pages = 1, >> + .vma = vma, >> + .address = addr, >> + .flags = PVMW_SYNC, >> + }; >> + >> + if (addr < vma->vm_start || addr >= vma->vm_end) >> + return -EFAULT; >> + if (!page_vma_mapped_walk(&pvmw)) >> + return -EFAULT; >> + page_vma_mapped_walk_done(&pvmw); >> + >> + return pvmw.address; >> +} > > I hate this name I hate that it's CONFIG_MEMORY_FAILURE only. Note that page_mapped_in_vma() is also KSM only. But I am curious why the function differs from what I quickly hacked together. -- Cheers, David