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 0318125B085; Sat, 8 Aug 2026 16:53:48 +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=1786208030; cv=none; b=p3ph8wpgql3dIu4m7GrRXbPOw/2bmTpKDe++if0h4HcY07agki2QC8FO4FB/cqsd3utr6VG27YHnX5Lq1oWbwViLJyMGwkkPpm3XzmeGFGpALW3AqEKzUvorNwWRiLqNYz+iMBjmy9/5Bs4ux1R/EsgmrdUQ/YC7eThFYCR+NDw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786208030; c=relaxed/simple; bh=gZRaFiBukDh3EZxovMXnuh60OG/dMwucPpfGT5gaD8Q=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=r8/d68ieCIUedVBN3UkiKXpV0XxTOO0h/dj04Bys4rkcGILPFFxlGK/x7zBnBTp75JApufEPptEoXLeQrc9h2MwdXns7XkK+Aem4BQ9hhajBjSi9wv4TiN7NwlmVI6HiBcgN66AJ+HHyl/tQks9MsUJHTaBU+YESMevu/ExX6MM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=TOCoY9zj; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="TOCoY9zj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 31CA01F000E9; Sat, 8 Aug 2026 16:53:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1786208028; bh=Ax9y1xfFH3chaxJ3oaEZM1cwYboqVTK0vjI4kxFoY/w=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=TOCoY9zjFfXkLgyDmi66obQzYFxAcWbQFoGdPmRWiDqW3K9Uod304Z0AuSwCz8zFY jnBfK+vzR6CYIXRaqDtfqt0uWSB39jpA7C5a8+WGZN30dnWG1pdY0ghByl6GVRJYBr LUP+dzlKMd7iWUtO02S92Hn+UPZKtAGOKQFwflx4= Date: Sat, 8 Aug 2026 09:53:47 -0700 From: Andrew Morton To: Hui Su Cc: andreyknvl@gmail.com, dvyukov@google.com, glider@google.com, kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, qiang1.zhang@intel.com, ryabinin.a.a@gmail.com, stable@vger.kernel.org, vincenzo.frascino@arm.com Subject: Re: [PATCH v2] kasan: fix cache shrink race with CPU hotplug Message-Id: <20260808095347.d9335a79ea6513d613784d48@linux-foundation.org> In-Reply-To: <20260808093803.3138988-3-sh_def@163.com> References: <20260808003921.fdb0df9ee4417b38f15e8c68@linux-foundation.org> <20260808093803.3138988-3-sh_def@163.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Sat, 8 Aug 2026 17:38:05 +0800 Hui Su wrote: > Thanks Andrew, > > On Sat, Aug 08, 2026 at 12:39:21AM -0700, Andrew Morton wrote: > > AI review suggests that there's a pre-existing quarantine_size > > accounting flaw later in this function: > > > > https://sashiko.dev/#/patchset/20260808031459.3032812-1-sh_def@163.com > > > > If true, I'm surprised this hasn't yet been reported. > > I'll take a closer look at this. If it turns out to be a real issue, > I'll send a separate patch since it's pre-existing and unrelated to the > hotplug race fix. > > > Also, I'd like to see a need_resched() wrapping that expensive > > > > /* Scanning whole quarantine can take a while. */ > > raw_spin_unlock_irqrestore(&quarantine_lock, flags); > > cond_resched(); > > raw_spin_lock_irqsave(&quarantine_lock, flags); > > Good point, that makes sense. Would you prefer that I fold this into a > v3 of this patch, or send it as a separate follow-up patch? Separate patches, please. One patch per concept.