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 44803606A32D for ; Sat, 14 Nov 2026 00:39:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=eZXJ2vJR Received: by kanga.kvack.org (Postfix) id 528616B05B1; Fri, 13 Nov 2026 19:39:27 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 4D8056B05B2; Fri, 13 Nov 2026 19:39:27 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3EE536B05B3; Fri, 13 Nov 2026 19:39:27 -0500 (EST) 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 1DB0C6B05B1 for ; Fri, 13 Nov 2026 19:39:27 -0500 (EST) Received: from smtpin28.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 8F6278026E for ; Sat, 14 Nov 2026 00:39:26 +0000 (UTC) X-FDA: 85431865932.28.F87B564 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf10.hostedemail.com (Postfix) with ESMTP id F10B6C0005 for ; Sat, 14 Nov 2026 00:39:24 +0000 (UTC) Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=eZXJ2vJR; spf=pass (imf10.hostedemail.com: domain of ojeda@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ojeda@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=1794616765; 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-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=TR03HYANH3JxjEWewr/Ab8mbFLXagZ4CIuGxSt6TVjM=; b=DrcVgQdRcTfl5fFtLi7/jF3iCjF1R0fHHRzD6CP3itOiXlwTgA/LcF9ylImzK0dR5U54f2 WWA2z++oSfU41m3memVwe1iHE0YN2BNfG6NUQxs8YErnq92dm84c2V8eOd1QqVg14b3LZv Qwr1H45leCzMUSoOvMoeQkGJwCOq2BY= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1794616765; b=bclf4Pe1M5/tQprU4qC+FDvyR/AXEStMcCgFeu5HZp+Wrc6McWH/92HzS8ojB8NueIPhP7 EJ7PRO9KS2NAFR2HzLn21nENQ1VDHK9mqJNGkrcN3uKrD4XVP8a/HKI3QuzJk6GHuZDzs6 b806PwW6/V+zfzSDSZXjBjE/Ycpv1dw= ARC-Authentication-Results: i=1; imf10.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=eZXJ2vJR; spf=pass (imf10.hostedemail.com: domain of ojeda@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ojeda@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 07EC9612C6; Sat, 14 Nov 2026 00:39:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1B0B51F000C4; Sat, 14 Nov 2026 00:39:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794616763; bh=TR03HYANH3JxjEWewr/Ab8mbFLXagZ4CIuGxSt6TVjM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=eZXJ2vJRLbnEG/8DsfpS1WuvlhpDqKP5Ad7yHWSwzESZK0n3LldVDoj2CztwVoCBh WTyP444vnzXJIHBKOWers+5ZvvFHF0FcSQqh1ztHVQEnRDIYzGQ7Fsld0tRoOkG+md qMjOIFLT9TK9QF3l3iksNJzcJp1Vcv7aCWz13sEtAz2rq6sqNqdCrHH4YAPoOQDDX/ V/liyDsiVNmhpiNwMmSQjiHF+gNZ+/mPG2yZwcEyUbOYevaxMdRiUuSG15wINfKhFc KcK+hIAcFVniTfpSyuSxGJFzfwl9hM1tMKtU8cX6G7+1T7DKRhIXJEwi0gI0gCSYQN 8uBXHdzKeJP3A== From: Miguel Ojeda To: gregkh@linuxfoundation.org Cc: 4ncienth@gmail.com, akpm@linux-foundation.org, azpijr@gmail.com, corbet@lwn.net, david@kernel.org, jannh@google.com, liam@infradead.org, ljs@kernel.org, mhocko@suse.com, patches@lists.linux.dev, pfalcato@suse.de, rdunlap@infradead.org, rppt@kernel.org, sashal@kernel.org, shakeel.butt@linux.dev, stable@vger.kernel.org, surenb@google.com, vbabka@kernel.org, linux-mm@kvack.org, Dave Hansen Subject: Re: [PATCH 7.3 463/507] mm/vma: avoid spurious write locks when mm->mm_lock_seq overflows Date: Sat, 14 Nov 2026 01:39:12 +0100 Message-ID: <20261114003912.82206-1-ojeda@kernel.org> In-Reply-To: <20261113153812.408825269@linuxfoundation.org> References: <20261113153812.408825269@linuxfoundation.org> X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: F10B6C0005 X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Stat-Signature: 8efztp6mwu15318redo55g1zf97oanc6 X-Rspam-User: X-HE-Tag: 1794616764-149950 X-HE-Meta: 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 WJP4MnSe VuUQZyhZQ2UkW7g/EC37cOJTqdE5iztyTZdIp/vCVfdfAXzTqho6e3EcVK4h+F6BWCy7WblCWaXU2y+qPx8fjv8ixaPehM8PHrwiBrtR5Kj7nFIOxX2k+0R1dmYz+4A8xOSDdGYqlpYDaR9hBfjD7qNOYtnPs35wVl5iQk/MI78SVwcfR0PF7eXOTVM+gCn8PK1cuNfLIlVPZD81Bn/xele7iGiapCiC1AtP/iQlHuskbsbwyrg+bQtLnGpzGsrgRwoM+wWNvybqXUYNa8yPBdt6QJM9k0kJJJ9oOv4ryXK9WjgWlsq6aBh0zuIbyXs93j6ahEaP+Sidikujz/WR1MrnA1KPRiyUvYvyP+a4abbcFSIUTua4z2cqHNjpx7665Pwho/iuDVoLoh2/qTl8COx2/2SVysyt3nu3I/i2lzLrrSup6vkr507zFL1qpz8HnLpqwTkNIpQsTUP/5NOQwZ10vysjVNnE2rb02s3ENqQTcmsOYku9+As0U6tmQ/QjbZ+/mAPoa0oldsSRtkpm24IWNDPXmd3aDfAg4BPFOCte65UIFKQE1E0ShkA1QoJFxydacNiUPjRjGH1dO8nvo2y0Lc/j8EFlxHlj5IlV0Z01TVqEj/3hpfA0wmw== 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 On Fri, 13 Nov 2026 10:52:47 -0500 Greg Kroah-Hartman wrote: > > @@ -589,6 +593,16 @@ static inline void vma_end_write_all(struct mm_struct *mm) > { > mmap_assert_write_locked(mm); > mm_lock_seqcount_end(mm); > + > + /* > + * VMA seqcounts are not updated on unlock, so once the mm seqcount has > + * wrapped, any VMA still carrying a sequence number from before the > + * wrap would satisfy __is_vma_write_locked() when that number comes > + * round again, and readers would not be excluded. Reset every VMA's > + * seqcount so that no stale value survives the wrap. > + */ > + if (unlikely(!mm->mm_lock_seq.sequence)) > + __mm_reset_vma_seqcounts(mm); > } In a UM ~defconfig build with LLVM: In file included from arch/um/kernel/asm-offsets.c:8: In file included from ./include/linux/audit.h:13: In file included from ./include/linux/ptrace.h:10: In file included from ./include/linux/pid_namespace.h:7: In file included from ./include/linux/mm.h:18: ./include/linux/mmap_lock.h:604:20: error: no member named 'mm_lock_seq' in 'struct mm_struct' 604 | if (unlikely(!mm->mm_lock_seq.sequence)) | ~~ ^ ./include/linux/compiler.h:77:42: note: expanded from macro 'unlikely' 77 | # define unlikely(x) __builtin_expect(!!(x), 0) | That exists only under `CONFIG_PER_VMA_LOCK` (commit 47e725702b0b ("mm: make per-VMA locks available universally") from Dave's series was not backported). I hope this helps! Cc: Andrew Morton Cc: Suren Baghdasaryan Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Vlastimil Babka Cc: Shakeel Butt Cc: linux-mm@kvack.org Cc: Jose A. Perez de Azpillaga Cc: Dave Hansen Cc: David Hildenbrand (Arm) Cheers, Miguel