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Tue, 10 Dec 2024 20:11:17 -0800 (PST) Received: from google.com ([2401:fa00:8f:203:4d97:9dbf:1a3d:bc59]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-7fd438e4bf1sm4517606a12.25.2024.12.10.20.11.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Dec 2024 20:11:16 -0800 (PST) Date: Wed, 11 Dec 2024 13:11:12 +0900 From: Sergey Senozhatsky To: Andrew Morton Cc: Sergey Senozhatsky , Minchan Kim , linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/6] zram: cond_resched() in writeback loop Message-ID: <20241211041112.GC2091455@google.com> References: <20241210105420.1888790-1-senozhatsky@chromium.org> <20241210105420.1888790-2-senozhatsky@chromium.org> <20241210165456.288ed82b8a66a08ac36a4d15@linux-foundation.org> 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-Disposition: inline In-Reply-To: <20241210165456.288ed82b8a66a08ac36a4d15@linux-foundation.org> On (24/12/10 16:54), Andrew Morton wrote: > On Tue, 10 Dec 2024 19:53:55 +0900 Sergey Senozhatsky wrote: > > > Writeback loop can run for quite a while (depending on > > wb device performance, compression algorithm and the > > number of entries we writeback), so we need to do > > cond_resched() there, similarly to what we do in > > recompress loop. > > > > ... > > > > --- a/drivers/block/zram/zram_drv.c > > +++ b/drivers/block/zram/zram_drv.c > > @@ -889,6 +889,8 @@ static ssize_t writeback_store(struct device *dev, > > next: > > zram_slot_unlock(zram, index); > > release_pp_slot(zram, pps); > > + > > + cond_resched(); > > } > > > > if (blk_idx) > > Should this be treated as a hotfix? With a -stable backport? Actually... can I please ask you to drop this [1] particular patch for now? The stall should not happen, because submit_bio_wait() is a rescheduling point (in blk_wait_io()). So I'm not sure why I'm seeing unhappy watchdogs. [1] https://lore.kernel.org/mm-commits/20241211005510.842DFC4CED6@smtp.kernel.org