From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794585696; b=K1D4K0bkVrc/VULHDErmmppCbZdZ+2n6qYGAzu3N8/Oj0DPbUue09WDDi51y/1jiOv98 NnVLawIowVHDNllvLRxwmMOrXa38ITJYWT1sPY0afLX9FydxIjWF67zu3FiWxn7nV13MU 98q2RAJjqZjSBvCFTbBUCNqUryxpEvsEhhJNPu7VOgtmvD9RcqEHGNZkqCk3Z34PvHow/ RMOzfeyHIqYkTURgGHQliJNDuWGxM2+8jQPsZQkys5Fvu9ro7DTSUxZ74ytD4LbFeaoaB riUHMnGhU4aPOnmPECRM47CleQlLhkSMoOzGcVqrIMAs/fqpM/JyoYURW2s1AN2+JFg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794585696; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=xZtLJxMtl03w2/LhbL1XWuPtWY1se8RzBb97i+vfhQE=; b=qa5+Pf5u323auSXwxOL2YPyN8q4YtoBU34b0pOMq/NgqKPVRT+c6AXjo+IK2wPlzTAvn x0288HGmdkWYZT0HduvfrD5uyBHom9aA2LSfpRe+nBz6rWOI8+9qEjGXWKrARx6+m8gso +lpZAG07OLQ8ce7lCLV5wPfLGUxOyK7zfyfP3cLfEXtdk4OhsPKUzbKc+qzdnCRDS5d7y bf5hreSLhOrqNyUXAef+KPJfwlzZkgBmsTWaVGPq2stWzCfcJSK5VVGJpdFX6TbIPURJp ovDfawB6Kd6jdcYizLSThj2lDQQdYeTSdTfHmqDqXOnpgDYFIWawlYVOeh3+SqT4alw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=uYsMWDWV; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D126F606A8B5; Fri, 13 Nov 2026 16:01:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=uYsMWDWV Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8215E1F000C4; Fri, 13 Nov 2026 16:01:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794585696; bh=xZtLJxMtl03w2/LhbL1XWuPtWY1se8RzBb97i+vfhQE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=uYsMWDWV/G79mUZEb2luie4gQM5bi2rZXQ0YUEoXEExWGwCD3B5bnLHebfM3M4Zye nm3KtrFQ97YJyM9xSmx21YO6BOAtEw2JaF0iU4BVk3G0EAbO+uN8pquOpqFMQrMV9J cw7MIgREDoEpGqyj9bVTkP3AV0NWxcZW6ATawMX8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Josef Bacik , "Gregory Price (Meta)" , Muhammad Usama Anjum , Lance Yang , Baolin Wang , "David Hildenbrand (Arm)" , Sasha Levin Subject: [PATCH 7.3 304/507] mm/khugepaged: always recheck the pmd in try_collapse_pte_mapped_thp() Date: Fri, 13 Nov 2026 10:50:08 -0500 Message-ID: <20261113153805.564975541@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261113153753.358973689@linuxfoundation.org> References: <20261113153753.358973689@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Josef Bacik [ Upstream commit aa72cf34d90da7019591ab67533a8ece8b41da2d ] try_collapse_pte_mapped_thp() drops the PTE lock after it has cleared the page table, and takes the PMD lock and the PTE lock to remove it. In between, MADV_DONTNEED with CONFIG_PT_RECLAIM can reclaim the page table. The pmd_same() check is supposed to handle this, but it is only done with CONFIG_SPLIT_PTE_PTLOCKS. Fix it by performing the check unconditionally. Fix generated by an LLM and sent by Josef Bacik in private. Fixes: 6375e95f381e ("mm: pgtable: reclaim empty PTE page in madvise(MADV_DONTNEED)") Cc: stable@vger.kernel.org Signed-off-by: Josef Bacik [ david: adjust description ] Reviewed-by: Gregory Price (Meta) Tested-by: Gregory Price (Meta) Tested-by: Muhammad Usama Anjum Link: https://patch.msgid.link/20261031-fixes_core-v3-15-d6437171ecc3@kernel.org Reviewed-by: Lance Yang Reviewed-by: Baolin Wang Signed-off-by: David Hildenbrand (Arm) Signed-off-by: Sasha Levin --- mm/khugepaged.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 16444bd7f1c0a..9cd468307841f 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -2037,12 +2037,11 @@ static enum scan_result try_collapse_pte_mapped_thp(struct mm_struct *mm, unsign /* step 4: remove empty page table */ if (!pml) { pml = pmd_lock(mm, pmd); - if (ptl != pml) { + if (ptl != pml) spin_lock_nested(ptl, SINGLE_DEPTH_NESTING); - if (unlikely(!pmd_same(pgt_pmd, pmdp_get_lockless(pmd)))) { - flush_tlb_mm(mm); - goto unlock; - } + if (unlikely(!pmd_same(pgt_pmd, pmdp_get_lockless(pmd)))) { + flush_tlb_mm(mm); + goto unlock; } } pgt_pmd = pmdp_collapse_flush(vma, haddr, pmd); -- 2.53.0