From nobody Sun Dec 14 21:54:18 2025 Received: from mail-pf1-f178.google.com (mail-pf1-f178.google.com [209.85.210.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 836A916D9B8 for ; Wed, 18 Dec 2024 06:35:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.178 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734503749; cv=none; b=EY5p26MhJ+Nb6/ZwypVupC6hlzeAb+N7t8YwXY5I4iNHpDlHSHd6rTGTDBNI5wtCsBVb8TfBF9rznIxLkISnCwfj4RfRS30apsbrC776kpYLBJ3jH6evd1FYUqzpF2QaP/mUJ1lz5yCoEoPxeYTgR/EzhlXV+JvNp5MZnOrHqHM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734503749; c=relaxed/simple; bh=Z7Q3IK3DKIWUy+W+tyBjH+edLwCfI7prnmKZg3nmKLI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lOhRrAaRT2got8LjB2kTThvfLiEJMzKc/F1Obt+XymHI4O9gjs3zRaA4qI/AQYlR5Iz3C2WqBDXGbldL0z/TckQ7zu96sZdeg9ld6Q/1ToeIJMpQuUvlv5YoMUycl8yPAsSvviRs5W7Sw9eBlf3/Rq0gckrk6L1nSSQBV0rtyF0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org; spf=pass smtp.mailfrom=chromium.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b=itiC4McN; arc=none smtp.client-ip=209.85.210.178 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=chromium.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="itiC4McN" Received: by mail-pf1-f178.google.com with SMTP id d2e1a72fcca58-725dc290c00so337942b3a.0 for ; Tue, 17 Dec 2024 22:35:47 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1734503747; x=1735108547; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=06dLgy7e/21/5Xh2W7aoiU59dLBqGpGpJ1upbma1LzU=; b=itiC4McNLozgYRFX0YlENXrPkn5xFk70b4yDp7AUJ700ajdDUODUy0e//sJgBNAP1T 77NdmAdaqP5OxpJJrfN2vAQF84y9MfPdnliwE3KXts8POVogmnaGy0QOTMPMCzy1lAxM 3uJgw9gdGVjZbRr7IhrzHD98YNvE+e/CFj1Q8= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1734503747; x=1735108547; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=06dLgy7e/21/5Xh2W7aoiU59dLBqGpGpJ1upbma1LzU=; b=PSHy/CYVB1tkbnobeOKA3qxkqXBxfWkLkZ0CY9aqchxSbHkqTHs960Y/Ulwv3BzF6L NlcdZmkUe6Z/bplMVLwDtIZBww7gj8SQISRhN44KjmWXU0+OxL41KdZeCT8sY1dDhCqA 65EIlvzOeALOi6wYi0N+RcLlzv1Mukpdm5MdnNf1jf64AnWdn3tPTqZoN6x8RyAD9iW0 eyLhuhNSGbjmya0f5nVzc0KwLhb4wtewNNfSKAa9GWkCCKUM2yY7F/1hWWxuDLLJ2wmg 0Abk25pbEx0LfDmx7YXo/pWtWB8snCavOp6kdJubov9SRJDutoHhyzSTvIz5svCZXE7t TfVg== X-Forwarded-Encrypted: i=1; AJvYcCUvCVs4pURlH2QkQTpAsb/KBxDUcH3VCuRrButuS8hkIIJ8fBI1i+TcYwl3ApigW9Pg17eoakohWCoGP1w=@vger.kernel.org X-Gm-Message-State: AOJu0Yz0QToF0hPmbxjJ+Vix7Ey7B2RUY97mMh0B8HGdwSGCE0nFxfIs +lNWwO4yPlFCgw2tKZ3XtSYJ+q/hoyTSEiY5QlTRRtyao1Aqn/d8oxe0hGmtTM2dhzL0SL/7sgo = X-Gm-Gg: ASbGncsFNe5aOaJbrQ6jy8svUMPQacapQPllNV8Xo8F1JNZhGqvAW+fiZJED2Dm4boQ miJUSEEHS5OjYE1vcFTwP/uBccr3lKlOw3IqEd7qqfeEongQ9fG50a0k9e0rZHo/KgrhHdfui2+ sSlswCnzYWmu7RZuYhEnGWLOv6ES00jhYiBEKRmoe4QceIc26FrhOTVfgb15PTJrhZkfspEJtFI y0llz/wN9LjE6sA84FImhMZqYqDl9cJqdnp8pWu2PDtIrvZa9jXbwzxFBM= X-Google-Smtp-Source: AGHT+IGf8g96scNATdGQ6vdl6cixlVJ73v6GuTOkPIuKqnPqyqGhnKzXBehwZAxlCiqlPr2dEdXf8A== X-Received: by 2002:a05:6a20:431b:b0:1e1:aef4:9cd9 with SMTP id adf61e73a8af0-1e5b5a7da91mr2332683637.23.1734503746822; Tue, 17 Dec 2024 22:35:46 -0800 (PST) Received: from localhost ([2401:fa00:8f:203:3bcc:36cc:b9fe:9379]) by smtp.gmail.com with UTF8SMTPSA id d2e1a72fcca58-72918ad5c07sm8023644b3a.60.2024.12.17.22.35.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 17 Dec 2024 22:35:46 -0800 (PST) From: Sergey Senozhatsky To: Andrew Morton Cc: Minchan Kim , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sergey Senozhatsky Subject: [PATCHv2 7/7] zram: cond_resched() in writeback loop Date: Wed, 18 Dec 2024 15:34:24 +0900 Message-ID: <20241218063513.297475-8-senozhatsky@chromium.org> X-Mailer: git-send-email 2.47.1.613.gc27f4b7a9f-goog In-Reply-To: <20241218063513.297475-1-senozhatsky@chromium.org> References: <20241218063513.297475-1-senozhatsky@chromium.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" zram writeback is a costly operation, because every target slot (unless ZRAM_HUGE) is decompressed before it gets written to a backing device. The writeback to a backing device uses submit_bio_wait() which may look like a rescheduling point. However, if the backing device has BD_HAS_SUBMIT_BIO bit set __submit_bio() calls directly disk->fops->submit_bio(bio) on the backing device and so when submit_bio_wait() calls blk_wait_io() the I/O is already done. On such systems we effective end up in a loop for_each (target slot) { decompress(slot) __submit_bio() disk->fops->submit_bio(bio) } Which on PREEMPT_NONE systems triggers watchdogs (since there are no explicit rescheduling points). Add cond_resched() to the zram writeback loop. Signed-off-by: Sergey Senozhatsky --- drivers/block/zram/zram_drv.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 7dd72b58e921..5b8e4f4171ab 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -884,6 +884,8 @@ static ssize_t writeback_store(struct device *dev, next: zram_slot_unlock(zram, index); release_pp_slot(zram, pps); + + cond_resched(); } =20 if (blk_idx) --=20 2.47.1.613.gc27f4b7a9f-goog