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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) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: BF7ABA0008 X-Stat-Signature: mzze84mpiq5sf6m6no89rciqz935jo9r X-Rspam-User: X-HE-Tag: 1786208029-863724 X-HE-Meta: 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 QxnenpNg SdEXnnMcycWq7Kw/AcqIxgikbnOaj1o9Hgjb8oBR3rIklGK3wQx0KGOt1GpVyRI7TwzB9ttahJdsPtojc7FWKfKATAae0/Q3s1axssxDQHv4z9sKKD1JeCgDBWqDMLCY7NHXVmb5onCRBqoeuTsJcgEqbq3/FeQG0zPaqI3VYPFRNpokSpqPmesu5HXiYlZyXnBCXkHlcVktPvEVw+jgc2K4BzVBlS8DqTXH1upxsxaww8jt4iUDaF6rl6F19a0SsC9dESacW8DM8IlHWeM4fUea5G57tMDx9jS1Si0ajAmo8r1CvghniK9gMcviKOkj7Zh0d1ZwwKU8KqQfWSKOnUH00YfpF1mDEsMSSABHJdmqCNzNLsYsG2uwW2x1KInJyfq5tDY70bFOg/J1CqXQS13BF8DOo3MXsr/qd Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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.