From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4D576C28D13 for ; Thu, 25 Aug 2022 10:43:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236033AbiHYKnn (ORCPT ); Thu, 25 Aug 2022 06:43:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60564 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230395AbiHYKnm (ORCPT ); Thu, 25 Aug 2022 06:43:42 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0E6C76052D for ; Thu, 25 Aug 2022 03:43:40 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id DCFBD6162A for ; Thu, 25 Aug 2022 10:43:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3B230C433D6; Thu, 25 Aug 2022 10:43:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1661424219; bh=/7bo9SbG7CLLg8/fBr29VIMSMsmowqTC9hBxofDJOo0=; h=Subject:To:Cc:From:Date:From; b=pA3Qkxdqb16K1YUSZ0H6XQuON/sOp2mUXVVnUHQ/TMMs+b6p0du8IhKM6vHtV5fyN wyLsU7ji7CIWpNZZ6OFMO4feYmgoJx4nqjvjIsIwNhVNklc3+/NU0LbUvPKQr7zqWB 3ib1VLGaGkt2jPv3LCdV8OS2SSb1kDqPpaj/NLps= Subject: FAILED: patch "[PATCH] Revert "zram: remove double compression logic"" failed to apply to 5.19-stable tree To: jirislaby@kernel.org, akpm@linux-foundation.org, avromanov@sberdevices.ru, ddrokosov@sberdevices.ru, jslaby@suse.cz, lczerner@redhat.com, minchan@kernel.org, ngupta@vflare.org, senozhatsky@chromium.org, stable@vger.kernel.org Cc: From: Date: Thu, 25 Aug 2022 12:43:35 +0200 Message-ID: <1661424215189156@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 5.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 37887783b3fef877bf34b8992c9199864da4afcb Mon Sep 17 00:00:00 2001 From: Jiri Slaby Date: Wed, 10 Aug 2022 09:06:09 +0200 Subject: [PATCH] Revert "zram: remove double compression logic" This reverts commit e7be8d1dd983156b ("zram: remove double compression logic") as it causes zram failures. It does not revert cleanly, PTR_ERR handling was introduced in the meantime. This is handled by appropriate IS_ERR. When under memory pressure, zs_malloc() can fail. Before the above commit, the allocation was retried with direct reclaim enabled (GFP_NOIO). After the commit, it is not -- only __GFP_KSWAPD_RECLAIM is tried. So when the failure occurs under memory pressure, the overlaying filesystem such as ext2 (mounted by ext4 module in this case) can emit failures, making the (file)system unusable: EXT4-fs warning (device zram0): ext4_end_bio:343: I/O error 10 writing to inode 16386 starting block 159744) Buffer I/O error on device zram0, logical block 159744 With direct reclaim, memory is really reclaimed and allocation succeeds, eventually. In the worst case, the oom killer is invoked, which is proper outcome if user sets up zram too large (in comparison to available RAM). This very diff doesn't apply to 5.19 (stable) cleanly (see PTR_ERR note above). Use revert of e7be8d1dd983 directly. Link: https://bugzilla.suse.com/show_bug.cgi?id=1202203 Link: https://lkml.kernel.org/r/20220810070609.14402-1-jslaby@suse.cz Fixes: e7be8d1dd983 ("zram: remove double compression logic") Signed-off-by: Jiri Slaby Reviewed-by: Sergey Senozhatsky Cc: Minchan Kim Cc: Nitin Gupta Cc: Alexey Romanov Cc: Dmitry Rokosov Cc: Lukas Czerner Cc: [5.19] Signed-off-by: Andrew Morton diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 92cb929a45b7..226ea76cc819 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -1146,14 +1146,15 @@ static ssize_t bd_stat_show(struct device *dev, static ssize_t debug_stat_show(struct device *dev, struct device_attribute *attr, char *buf) { - int version = 2; + int version = 1; struct zram *zram = dev_to_zram(dev); ssize_t ret; down_read(&zram->init_lock); ret = scnprintf(buf, PAGE_SIZE, - "version: %d\n%8llu\n", + "version: %d\n%8llu %8llu\n", version, + (u64)atomic64_read(&zram->stats.writestall), (u64)atomic64_read(&zram->stats.miss_free)); up_read(&zram->init_lock); @@ -1351,7 +1352,7 @@ static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec, { int ret = 0; unsigned long alloced_pages; - unsigned long handle = 0; + unsigned long handle = -ENOMEM; unsigned int comp_len = 0; void *src, *dst, *mem; struct zcomp_strm *zstrm; @@ -1369,6 +1370,7 @@ static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec, } kunmap_atomic(mem); +compress_again: zstrm = zcomp_stream_get(zram->comp); src = kmap_atomic(page); ret = zcomp_compress(zstrm, src, &comp_len); @@ -1377,20 +1379,39 @@ static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec, if (unlikely(ret)) { zcomp_stream_put(zram->comp); pr_err("Compression failed! err=%d\n", ret); + zs_free(zram->mem_pool, handle); return ret; } if (comp_len >= huge_class_size) comp_len = PAGE_SIZE; - - handle = zs_malloc(zram->mem_pool, comp_len, - __GFP_KSWAPD_RECLAIM | - __GFP_NOWARN | - __GFP_HIGHMEM | - __GFP_MOVABLE); - + /* + * handle allocation has 2 paths: + * a) fast path is executed with preemption disabled (for + * per-cpu streams) and has __GFP_DIRECT_RECLAIM bit clear, + * since we can't sleep; + * b) slow path enables preemption and attempts to allocate + * the page with __GFP_DIRECT_RECLAIM bit set. we have to + * put per-cpu compression stream and, thus, to re-do + * the compression once handle is allocated. + * + * if we have a 'non-null' handle here then we are coming + * from the slow path and handle has already been allocated. + */ + if (IS_ERR((void *)handle)) + handle = zs_malloc(zram->mem_pool, comp_len, + __GFP_KSWAPD_RECLAIM | + __GFP_NOWARN | + __GFP_HIGHMEM | + __GFP_MOVABLE); if (IS_ERR((void *)handle)) { zcomp_stream_put(zram->comp); + atomic64_inc(&zram->stats.writestall); + handle = zs_malloc(zram->mem_pool, comp_len, + GFP_NOIO | __GFP_HIGHMEM | + __GFP_MOVABLE); + if (!IS_ERR((void *)handle)) + goto compress_again; return PTR_ERR((void *)handle); } @@ -1948,6 +1969,7 @@ static int zram_add(void) if (ZRAM_LOGICAL_BLOCK_SIZE == PAGE_SIZE) blk_queue_max_write_zeroes_sectors(zram->disk->queue, UINT_MAX); + blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, zram->disk->queue); ret = device_add_disk(NULL, zram->disk, zram_disk_groups); if (ret) goto out_cleanup_disk; diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h index 158c91e54850..80c3b43b4828 100644 --- a/drivers/block/zram/zram_drv.h +++ b/drivers/block/zram/zram_drv.h @@ -81,6 +81,7 @@ struct zram_stats { atomic64_t huge_pages_since; /* no. of huge pages since zram set up */ atomic64_t pages_stored; /* no. of pages currently stored */ atomic_long_t max_used_pages; /* no. of maximum pages stored */ + atomic64_t writestall; /* no. of write slow paths */ atomic64_t miss_free; /* no. of missed free */ #ifdef CONFIG_ZRAM_WRITEBACK atomic64_t bd_count; /* no. of pages in backing device */