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From: Chengming Zhou In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 988A51A0013 X-Stat-Signature: nbi6im9qdjpnfsn73cthff7i9jxh9jeu X-HE-Tag: 1709134694-794939 X-HE-Meta: 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2024/2/28 23:24, Matthew Wilcox wrote: > On Wed, Feb 28, 2024 at 03:18:32PM +0000, Chengming Zhou wrote: >> Now the release of zswap pool is controlled by percpu_ref, its release >> callback (__zswap_pool_empty()) will be called when percpu_ref hit 0. >> But this release callback may potentially be called from RCU callback >> context by percpu_ref_kill(), which maybe in the interrupt context. >> >> So we need to use spin_lock_irqsave() and spin_unlock_irqrestore() >> in the release callback: __zswap_pool_empty(). In other task context >> places, spin_lock_irq() and spin_unlock_irq() are enough to avoid >> potential deadlock. > > RCU callback context is BH, not IRQ, so it's enough to use > spin_lock_bh(), no? You're right, it's the softirq context, so spin_lock_bh() is enough. Thanks!