From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id C4D44606A31C for ; Sat, 31 Oct 2026 09:44:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=SBYWyFJB Received: by kanga.kvack.org (Postfix) id BBBF16B05CD; Sat, 31 Oct 2026 05:44:12 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B932E6B05CE; Sat, 31 Oct 2026 05:44:12 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AD01D6B05CF; Sat, 31 Oct 2026 05:44:12 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 821946B05CD for ; Sat, 31 Oct 2026 05:44:12 -0400 (EDT) Received: from smtpin27.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 02DA41404D2 for ; Sat, 31 Oct 2026 09:44:11 +0000 (UTC) X-FDA: 85382435544.27.E0595D6 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf18.hostedemail.com (Postfix) with ESMTP id 357F81C0004 for ; Sat, 31 Oct 2026 09:44:09 +0000 (UTC) Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=SBYWyFJB; spf=pass (imf18.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1793439850; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=dD8bNaZIuViD1rMmSH8A86u/ZWtm1YEV/epD2uKBbxE=; b=br0dTKLNbl1u/vr47pPy9gLYHv01/gDub5ummn16SOq9knJPrcMUMnGxLrEibz7Iq6cEq/ jRkCqrxTQh+Hh08/jZJV+11m1FNHkdTDBhC8GHNFL7CjANxNiMOpAOAZYV2DWjbVlBucY9 B5EZttH8jk25hX7PO69/Y8ppELz61sQ= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793439850; b=JxkHvmF/u7Y/J2dFVJ5b5KneJJmw9RnNnjweJ8DeZJ2hjbv/T9J81TVjoItgOxtmMffOGm wvqSCO1K8r8OE6aGYITaLlyyLU/LmBaMDaswWfCYPLu/8MhXwNl3fLZ1Ph7FhQuU7CVKGe IAkRs+tOiC7EczVk9c9BAEY94h/G0sI= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=SBYWyFJB; spf=pass (imf18.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 64362406FB; Sat, 31 Oct 2026 09:44:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BBBC31F0093A; Sat, 31 Oct 2026 09:43:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793439849; bh=dD8bNaZIuViD1rMmSH8A86u/ZWtm1YEV/epD2uKBbxE=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=SBYWyFJBjrqmvQU0SLK/yXNYDG03UfEHLHBfhq+cgw3Mp75MofH2A8dc6wPjeEDVv OgsCgMr8avGx4SVXvGmJOt4L0WLdm8QTqbVfd3IgM2F9nzP1NKoikT78JhjLalaX6y MJa8/PAIKKtuVGZ6zyGm2qn8asC2gEIT2/RlnUQdveNPyGdqArZM+nJ3oFiB4QJBUD FqHedcFM3LOFsdKvRRAW7qIWlFNsNLMIvP2f0hRzi9q6829DtyPX0OMj/JaKxv8REN 3jH/Ga4Nqjvn8Vw5Hr0RDErkQgv1hA578/T4CTyi0+/C11MmrghwGE7RVwyCq1+EpW sR34AEi7oNxPg== From: "David Hildenbrand (Arm)" Date: Sat, 31 Oct 2026 10:39:44 +0100 Subject: [PATCH v3 15/47] mm/khugepaged: always recheck the pmd in try_collapse_pte_mapped_thp() X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261031-fixes_core-v3-15-d6437171ecc3@kernel.org> References: <20261031-fixes_core-v3-0-d6437171ecc3@kernel.org> In-Reply-To: <20261031-fixes_core-v3-0-d6437171ecc3@kernel.org> To: Andrew Morton , Johannes Weiner , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kees Cook , Peter Zijlstra , Jann Horn , Pedro Falcato , Hugh Dickins , Pasha Tatashin , Pratyush Yadav , "Matthew Wilcox (Oracle)" , Jan Kara , Zi Yan , Lance Yang , Rik van Riel , Harry Yoo , Alistair Popple , Nico Pache , Ryan Roberts , Dev Jain , Usama Arif , Kiryl Shutsemau , Matthew Brost , John Hubbard , Peter Xu , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Oscar Salvador , Minchan Kim , Muchun Song , Xu Xin , Chengming Zhou , Chris Li , Kemeng Shi , Nhat Pham , Youngjun Park , Gregory Price , Joshua Hahn , Rakie Kim , Ying Huang , Jason Gunthorpe Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, Josef Bacik , stable@vger.kernel.org, Muhammad Usama Anjum , "David Hildenbrand (Arm)" X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1665; i=david@kernel.org; h=from:subject:message-id; bh=CS7nU47snOvzHXKT1Jq5YnXJ98oWY8rgSlPg1efCrZ0=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLKebk9PenzlJu+Me5oLPjgcPt+x3vBE0sRXv9/FJ7pPE V46WSm6vaOUhUGMg0FWTJElKPi+wcuX62qr3fiYYeawMoEMYeDiFICJnF7PyNBhvkr/s0eeQtOS xA+ZX8KZxEMW5rmvFv7Ty3PvlKhu4G9Ghhu37Loa9P4Ieh2Osa9PXXbdul0vIGFp3yn3w0uKr5Z OYAYA X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 357F81C0004 X-Stat-Signature: i1xtzeizejjq5shjqocorgtkt68qsxum X-Rspam-User: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=4.0.1 X-HE-Tag: 1793439849-230766 X-HE-Meta: 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 6ITKGLjG 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 From: Josef Bacik 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 Signed-off-by: David Hildenbrand (Arm) --- mm/khugepaged.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 3a6f4b7b28453..81496887d827e 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -2013,12 +2013,11 @@ 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); -- 2.43.0