From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.esperi.org.uk (icebox.esperi.org.uk [81.187.191.129]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1B50D158535 for ; Sun, 7 Sep 2025 15:25:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=81.187.191.129 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757258708; cv=none; b=CtJg//DBJTpqpLzWH7O7Zi6Z2+B7IKjs8qEmtgpno8Ijij5+WRWqTV/dIdGxo3xvKiB9nDb+i2uZiR8BsGg9gNKdOkmcsmTgbWjjlMOIG9HUC9mCNAO9yuWdVohM7GU7fYT2BsmivhY0yjFkcA0f8SaTCaHubSHxnHTUKfqhJIg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757258708; c=relaxed/simple; bh=2mLggywtNyhjEokMa3tAMhBjBZweVsYv6qUz7XP1pGQ=; h=From:To:Subject:Date:Message-ID:MIME-Version:Content-Type; b=Zvl6Mxe4nD3Akh/How/dyTDyPeyWRzqq7HuQrU4JqMN7DhyJSTVOEupp0BImZu14MKHmse4Kk59H/WhmtCGTKF23nV2qANnPucfpu9qGw+R7SDdTMipFcBZcbtjjJh1dq1RnkZ78QwpRCoGvuJK8AzhSmcqffkF9qKl4xKmQT48= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=esperi.org.uk; spf=pass smtp.mailfrom=esperi.org.uk; arc=none smtp.client-ip=81.187.191.129 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=esperi.org.uk Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=esperi.org.uk Received: from loom (nix@sidle.srvr.nix [192.168.14.8]) by mail.esperi.org.uk (8.17.2/8.17.2) with ESMTPS id 587EbotS029876 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO) for ; Sun, 7 Sep 2025 15:37:51 +0100 From: Nix To: linux-bcache@vger.kernel.org Subject: gen wraparound warning: is this a problem? Emacs: no job too big... no job. Date: Sun, 07 Sep 2025 15:37:50 +0100 Message-ID: <87a536e3b5.fsf@esperi.org.uk> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.3 (gnu/linux) Precedence: bulk X-Mailing-List: linux-bcache@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-DCC-wuwien-Metrics: loom 1290; Body=1 Fuz1=1 So, out of the blue, I just got this for my long-standing writearound bcache setup (which covers my rootfs and $HOME, so I kind of care that it keeps working): [3997629.262213] WARNING: CPU: 0 PID: 222478 at drivers/md/bcache/alloc.c:81 bch_inc_gen+0x3c/0x40 [3997629.278998] Modules linked in: vfat fat intel_uncore_frequency intel_uncore_frequency_common [3997629.295763] CPU: 0 UID: 0 PID: 222478 Comm: kworker/0:9 Tainted: G W 6.15.6-00002-g0d4613ee4427-dirty #2 NONE [3997629.329334] Tainted: [W]=WARN [3997629.345701] Hardware name: Intel Corporation S2600CWR/S2600CWR, BIOS SE5C610.86B.01.01.1029.090220201031 09/02/2020 [3997629.362413] Workqueue: bcache bch_data_insert_keys [3997629.378983] RIP: 0010:bch_inc_gen+0x3c/0x40 [3997629.395389] Code: 0f 89 c2 48 89 e5 2a 56 07 0f b6 b1 1a 06 00 00 40 38 f2 0f 42 d6 88 91 1a 06 00 00 48 8b 17 80 ba 1a 06 00 00 60 77 02 5d c3 <0f> 0b 5d c3 0f 1f 44 00 00 55 48 89 e5 41 54 53 48 8b 87 30 03 00 [3997629.428514] RSP: 0018:ffffa7dba31b7a00 EFLAGS: 00010202 [3997629.444857] RAX: 0000000000000045 RBX: 000007ffffffffff RCX: ffff9e5e0d140000 [3997629.461276] RDX: ffff9e5e0d140000 RSI: 0000000000000060 RDI: ffff9e5e00ee4000 [3997629.477509] RBP: ffffa7dba31b7a00 R08: 0000000000000001 R09: 0000000000000000 [3997629.493394] R10: 000e33d2971e5c02 R11: 0000000000000004 R12: 0000000000000002 [3997629.509021] R13: 0000000000000001 R14: ffffa7dba31b7ac8 R15: ffff9e5e149b5000 [3997629.524515] FS: 0000000000000000(0000) GS:ffff9e7d6d275000(0000) knlGS:0000000000000000 [3997629.539853] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [3997629.555063] CR2: 00000000328da018 CR3: 00000007d6c41002 CR4: 00000000003726f0 [3997629.570252] Call Trace: [3997629.585190] [3997629.599881] make_btree_freeing_key+0xf0/0x130 [3997629.614450] btree_split+0x4c9/0x6b0 [3997629.628797] ? cpu_rmap_get+0x40/0x40 [3997629.642981] bch_btree_insert_node+0x2c2/0x390 [3997629.657004] btree_insert_fn+0x24/0x50 [3997629.670750] bch_btree_map_nodes_recurse+0x3c/0x170 [3997629.684371] ? bch_btree_insert_check_key+0x1b0/0x1b0 [3997629.697940] ? bch_btree_ptr_bad+0x49/0xe0 [3997629.711187] ? bch_btree_node_get.part.0+0x79/0x2c0 [3997629.724089] ? rwsem_wake.isra.0+0x70/0x70 [3997629.736874] bch_btree_map_nodes_recurse+0xf3/0x170 [3997629.749516] ? bch_btree_insert_check_key+0x1b0/0x1b0 [3997629.762012] __bch_btree_map_nodes+0x189/0x1a0 [3997629.774179] ? bch_btree_insert_check_key+0x1b0/0x1b0 [3997629.786202] bch_btree_insert+0xca/0x130 [3997629.797987] ? ipi_sync_rq_state+0x40/0x40 [3997629.809575] bch_data_insert_keys+0x36/0xe0 [3997629.820919] process_one_work+0x14b/0x300 [3997629.831940] worker_thread+0x2c3/0x400 [3997629.842820] ? flush_rcu_work+0x40/0x40 [3997629.853452] kthread+0xe8/0x1e0 [3997629.863718] ? kthread_cancel_delayed_work_sync+0x20/0x20 [3997629.873923] ret_from_fork+0x36/0x50 [3997629.883866] ? kthread_cancel_delayed_work_sync+0x20/0x20 [3997629.893642] ret_from_fork_asm+0x11/0x20 [3997629.903209] [4001476.794864] WARNING: CPU: 10 PID: 408 at drivers/md/bcache/alloc.c:81 __bch_invalidate_one_bucket+0xba/0xc0 [4001476.804157] Modules linked in: vfat fat intel_uncore_frequency intel_uncore_frequency_common [4001476.813375] CPU: 10 UID: 0 PID: 408 Comm: bcache_allocato Tainted: G W 6.15.6-00002-g0d4613ee4427-dirty #2 NONE [4001476.832090] Tainted: [W]=WARN [4001476.841130] Hardware name: Intel Corporation S2600CWR/S2600CWR, BIOS SE5C610.86B.01.01.1029.090220201031 09/02/2020 [4001476.850542] RIP: 0010:__bch_invalidate_one_bucket+0xba/0xc0 [4001476.859914] Code: 24 48 89 f2 48 8b 78 08 4c 89 e6 48 29 ca 48 b9 ab aa aa aa aa aa aa aa 48 c1 fa 02 48 0f af d1 e8 fb c6 01 00 e9 6a ff ff ff <0f> 0b eb 96 0f 0b 0f 1f 44 00 00 55 48 89 e5 41 54 49 89 f4 53 48 [4001476.879592] RSP: 0018:ffffa7db80a2fe50 EFLAGS: 00010202 [4001476.889576] RAX: ffff9e5e0d140000 RBX: ffffa7db80976af0 RCX: 0000000000000061 [4001476.899666] RDX: ffff9e5e0d140000 RSI: ffffa7db80976af0 RDI: ffff9e5e00ee4000 [4001476.909659] RBP: ffffa7db80a2fe60 R08: ffffa7db808e82a8 R09: 0000000000000102 [4001476.919519] R10: 000000000000040b R11: ffff9e5e00ee0000 R12: ffff9e5e00ee4000 [4001476.929322] R13: 00000000000003ff R14: ffffa7db808ff30c R15: ffff9e5e00ee4000 [4001476.938978] FS: 0000000000000000(0000) GS:ffff9e7d6d4f5000(0000) knlGS:0000000000000000 [4001476.948860] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [4001476.958735] CR2: 00007f8d3fbff6d8 CR3: 00000007d6c41006 CR4: 00000000003726f0 [4001476.968744] Call Trace: [4001476.978687] [4001476.988541] bch_invalidate_one_bucket+0x17/0x80 [4001476.998509] bch_allocator_thread+0xb05/0xc90 [4001477.008447] ? bch_invalidate_one_bucket+0x80/0x80 [4001477.018391] kthread+0xe8/0x1e0 [4001477.028309] ? kthread_cancel_delayed_work_sync+0x20/0x20 [4001477.038348] ret_from_fork+0x36/0x50 [4001477.048346] ? kthread_cancel_delayed_work_sync+0x20/0x20 [4001477.058448] ret_from_fork_asm+0x11/0x20 [4001477.068493] These both map to this in bch_inc_gen(): WARN_ON_ONCE(ca->set->need_gc > BUCKET_GC_GEN_MAX); Is this something the admin needs to do something about? (And, if it's not and bcache recovers smoothly, as so far it seems to -- though I haven't tried to remount it since the warning -- why do we warn about it at all?)