From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=95.215.58.168 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794397161; b=Xbwaqc90NrFl3SfHX8Zhp5imWZ462dfm9CZ1p4DUeEhq4Wb0dLMkbgqYW12NCmmC0g4L sua2xOcoI6cqlATXuWCl0Yn4D9si8ixJqUDEfQIqKbTJnXOQ/L9tBx+q2toRzLadIgqFw I9fSSffgBCDgj5nzQJiBYseGVa0y8zwvwPSmrc3A2s0Pm61ZBIPSM7LKlV/fvdFfznXWJ jrbIcmsNdx0bdtGgYKlafuES03IENfXAdH6zdh9Fvbvvr2geY+LUQ74gYwpFTmcLKccB0 DmmTpR6joMOqQNesAigKkDVERlVIiooSb350O5UeIWyo3X503PDJzII5gFc4l11hxPw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794397161; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:From:To:Cc:Subject:Date:Message-ID: X-Mailer:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding; bh=2saoVbYFwvaTsDZ1OYoBWs5gUVifzn045/gtvbvuIH4=; b=sEcqgi8pnk3V/J8ZsJBGIFbBcPBhtJVkYDYfP9xNalkG3yNaNsGs180L9CRXoT9Mc9OE a9KOhMAN6O0E/cQiK1zYsQS3H771Ee9+h5BXjHW0zi3TjE8YXA2hQ2pGqIyRwIxYC3VPY z+ZTeiZIFprT5zILLTz7L9HV/KiszOLazAiKm3NWYsGcWZXPgPuBqvIx86L0IuGxlMWM0 H+5QbO2oh0hYZHhtxhtAkUQtyLs3OyUAvtBT0mwtIOZnlNiPhwtPUYEjeXMx5M/N1A28B jpt3eYdmK0wUrk43i+GiihvCfOGGryCupTJTFPaiZ+fdhjoKb/dZ6zhdXFgH/TYrSGw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=ol4gTM4U; arc=none smtp.remote-ip=95.215.58.168 Received: from mta1.migadu.com (out-168.mta1.migadu.com [95.215.58.168]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6E240606A889 for ; Wed, 11 Nov 2026 11:39:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 6E240606A889 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=ol4gTM4U X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=RMq5jEADKeGNruhLoquiDuSfixBjLOzms6+A0cUPnr4=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1794397158; v=1; x=1795001958; b=ol4gTM4U5KHxFLvbS+cFMtU47Q7/IWQU1DlbzZnCaIGuqvVwK8Gm6MEkpVq4G7ECizDEl9E3 uqh1sQmp0WJI5PGBncqlTXnpqiUpo+twikOuRi1Oi/DbxH7fR16Pyb9NWc8P1ZJinvi/KAEdaFq TeNsUe9L0cjn8h0t+pXt6vpw= X-Envelope-To: linux-kernel@vger.kernel.org Received: by mta10.migadu.com with ESMTPS id 2797f348b581f3be; Wed, 11 Nov 2026 11:39:18 +0000 X-Mizu-Trace-ID: 2797f348b581f3be X-Migadu-Flow: FLOW_OUT From: Usama Arif To: Andrew Morton , apopple@nvidia.com, byungchul@sk.com, david@kernel.org, gourry@gourry.net, jannh@google.com, joshua.hahnjy@gmail.com, liam@infradead.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, ljs@kernel.org, matthew.brost@intel.com, mhocko@suse.com, pfalcato@suse.de, rppt@kernel.org, surenb@google.com, vbabka@kernel.org, ying.huang@linux.alibaba.com, ziy@nvidia.com, kas@kernel.org, hannes@cmpxchg.org, riel@surriel.com, shakeel.butt@linux.dev, kernel-team@meta.com, baolin.wang@linux.alibaba.com, Nico Pache , ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev Cc: Usama Arif , stable@vger.kernel.org Subject: [PATCH 2/3] fs/proc/task_mmu: don't read young/dirty from a non-present PMD in smaps Date: Wed, 11 Nov 2026 03:38:30 -0800 Message-ID: <20261111113904.650722-3-usama.arif@linux.dev> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261111113904.650722-1-usama.arif@linux.dev> References: <20261111113904.650722-1-usama.arif@linux.dev> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit smaps_pmd_entry() passes pmd_young(*pmd) and pmd_dirty(*pmd) to smaps_account() for every PMD, including migration and device-private entries, where those bits hold part of the swap offset rather than accessed/dirty state. smaps_pte_entry() only reads them when the entry is present. On x86_64 the offset is stored inverted across bits 9-58, which overlap _PAGE_SAVED_DIRTY, so pmd_dirty() returns garbage: a clean 2MB device-private mapping is accounted as 2048 kB dirty, and lazyfree accounting is suppressed. pgtable_64.h also warns that the hardware can set the accessed and dirty bits on non-present entries by mistake. Only read the bits when the PMD is present. Fixes: c94b6923fa0a ("/proc/PID/smaps: Add PMD migration entry parsing") Cc: stable@vger.kernel.org Signed-off-by: Usama Arif --- fs/proc/task_mmu.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 22361607020d1..c0d391186c2b8 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1019,13 +1019,15 @@ static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr, struct vm_area_struct *vma = walk->vma; bool locked = !!(vma->vm_flags & VM_LOCKED); struct page *page = NULL; - bool present = false; + bool present = false, young = false, dirty = false; struct folio *folio; if (pmd_none(*pmd)) return; if (pmd_present(*pmd)) { page = vm_normal_page_pmd(vma, addr, *pmd); + young = pmd_young(*pmd); + dirty = pmd_dirty(*pmd); present = true; } else if (unlikely(thp_migration_supported())) { const softleaf_t entry = softleaf_from_pmd(*pmd); @@ -1045,8 +1047,7 @@ static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr, else mss->file_thp += HPAGE_PMD_SIZE; - smaps_account(mss, page, true, pmd_young(*pmd), pmd_dirty(*pmd), - locked, present); + smaps_account(mss, page, true, young, dirty, locked, present); } #else static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr, -- 2.53.0-Meta