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Wed, 05 Aug 2026 00:30:54 -0700 (PDT) Received: from google.com ([2a00:79e0:2031:6:8002:2a47:a704:5a58]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-38fee066b9fsm3665743a91.17.2026.08.05.00.30.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Aug 2026 00:30:53 -0700 (PDT) Date: Wed, 5 Aug 2026 16:30:49 +0900 From: Sergey Senozhatsky To: "Barry Song (Xiaomi)" Cc: senozhatsky@chromium.org, akpm@linux-foundation.org, bigeasy@linutronix.de, hdanton@sina.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, minchan@kernel.org, ryncsn@gmail.com, yosry.ahmed@linux.dev, surenb@google.com, Dongdong Zhang Subject: Re: [RFC PATCH] zram: avoid preemption with CPU-based compression backends Message-ID: References: <20260805005545.66112-1-baohua@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260805005545.66112-1-baohua@kernel.org> X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 337F21C0007 X-Stat-Signature: 6oswn95zemk84a6n7kn36qmi78q6jysn X-Rspam-User: X-HE-Tag: 1785915055-827346 X-HE-Meta: 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 pqo6MFgY qUJZLvlAnPfdcqds2LWLOUTMiBMgQzkjStrxMYGzXjMir8/xUdNCrAndDPaEMHecpK6UpjCj4yO34sno30mxeGZWphfWD5B2LyYyvAeKiRL3a4bjUg9Pn9MuG4Y3ycbdeSEHtPz1VZN+Sy778dk8jmI8OHutD8D0PemcYNEXC6AHukrOe4etEsNOjrG2LGOM2UYjw+aieMvCkiXvHTPBTuKlmGrlAbZ4kNBHYw0gMAFdXAwdGvpswM0N9YgtF2rnDKmFPbMkgf3PN92iWd7IdK5cqtV66QSMH7nfNHtIVozrsRD5TPQULqL0BTm/xOH+t4m0spevILbON72Ojaf0YrzNN19FoBiHJDoL+76iDLNKKtKNG0lBSKVK4Lv6BMCW7iCXd Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On (26/08/05 08:55), Barry Song (Xiaomi) wrote: > @@ -128,14 +128,20 @@ struct zcomp_strm *zcomp_stream_get(struct zcomp *comp) > * so then unlock and re-try on the current CPU. > */ > mutex_lock(&zstrm->lock); > + if (!comp->ops->async && !IS_ENABLED(CONFIG_PREEMPT_RT)) > + preempt_disable(); We take slot_lock(), which is preemptible, under stream lock on some paths. > if (likely(zstrm->buffer)) > return zstrm; > mutex_unlock(&zstrm->lock); > } > }