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Tue, 10 Feb 2026 19:07:35 -0800 (PST) Received: from google.com ([2a00:79e0:2031:6:ec5:3497:e96b:e7be]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-8249e3af080sm423001b3a.15.2026.02.10.19.07.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Feb 2026 19:07:34 -0800 (PST) Date: Wed, 11 Feb 2026 12:07:31 +0900 From: Sergey Senozhatsky To: Matthew Wilcox Cc: Sergey Senozhatsky , Andrew Morton , Minchan Kim , Brian Geffon , Jens Axboe , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-mm@kvack.org, Richard Chang , David Stevens Subject: Re: [PATCH] zram: drop slot trylock and miss_free Message-ID: References: <20260210035045.3817297-1-senozhatsky@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Queue-Id: B17CA80006 X-Rspamd-Server: rspam07 X-Stat-Signature: cmorsjrpgqja8eyb3ck9ukybkb36iygu X-HE-Tag: 1770779256-279195 X-HE-Meta: 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 pw7OhXNJ CCkHPrcy1RRbHl52JpFguLElC7jnE9IwJpz+HuuNsDcAjQscaOrbC7jXkels6suDC0na7vMqUbj2TmC1OQG7zdHzJV0Q4oCm2uPE/MZUGldl3f8TkAiGqxxvWyfqrZSaTbWqJU5Z1jDknRbIR8gFSlPYzZ6y8w1HemnS8ozxwKYOi2OQmYSRVLLboYwUYz3UZBARXPYJ6D9K4QIgHFzBTo8gmpkJQjzAp8gvV5iGD6zp2mpRXU8Ar58xyfPdSPOLqkV3cteJ05QCFt/Eg8jZmFT0lLHb0PlO1bK4ftOowYIud1CScKsog9yhp+/TKiMnexps/CW78uVRgF0um56wrsGaHfyKdpyYxEtk7aHYwj969utmkJHtUYIheQ3LZDCRW/cYqxh1QeknrWrVN0x50UoYILg== 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 (26/02/10 14:29), Matthew Wilcox wrote: > On Tue, Feb 10, 2026 at 12:50:37PM +0900, Sergey Senozhatsky wrote: > > @@ -1943,15 +1927,9 @@ static ssize_t debug_stat_show(struct device *dev, > > { > > int version = 1; > > struct zram *zram = dev_to_zram(dev); > > - ssize_t ret; > > > > guard(rwsem_read)(&zram->dev_lock); > > - ret = sysfs_emit(buf, > > - "version: %d\n0 %8llu\n", > > - version, > > - (u64)atomic64_read(&zram->stats.miss_free)); > > - > > - return ret; > > + return sysfs_emit(buf, "version: %d\n0 0\n", version); > > } > > You don't need the dev_lock any more to just report the version. True. I'll think if I want to send out a v2 with just miss_free removal. The objective was to remove trylock (and all the things around it), but trylock has to stay. While we cannot have slot_lock(42) slot_lock(42) any more, the slot-free-notify is still called under spin_lock, and slot_lock() might_sleep(). So trylock has to stay around. > And should the version be changed now that you've changed the format to > not include miss_free? The idea was to bump the version only when the format changes. You normally (well, technically "always", since e914d8f00391) would see 0 miss_free, and with the patch it's just a hard-coded 0. Thanks for taking a look, Matthew.