From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 86C9B39903B; Tue, 21 Jul 2026 18:16:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784657792; cv=none; b=Q9yiKsIzDVyP0aW8eaRfS/xrDvyv0k718ewthqPlR2LZoVyJ+M/obj9AT9MhMyXWRsFiF9mSkayHT1pCzKjeQlnDNjv3+WnUCM7aNbcPchBak1YjnMs+je1PQ+Qt4JAKCzygcdnOcGmNqrcr3ECkEb7qF8jfp2kif52/8LjJCd0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784657792; c=relaxed/simple; bh=5/dH4h8DQHVgGbfXGvlDW2JoPnc5DqwHUwNculpAzJg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ZD3fq2ss3DcAKK2YmTWtxPAK+w6L8x/TJUkDJ1UuJdrXccuDkXfeBUKDUk3yUlS1oqpxuv9vQIJBZb3BoKEenc4n0yec9Ivy6IUvMfczuNUhhaago0kNipqzDlqeo6+Ydkmh2xRh525VLRE5aceET5klosER+2Qtc8O+p7es0h8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=IiVk2vlQ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="IiVk2vlQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6898B1F000E9; Tue, 21 Jul 2026 18:16:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784657788; bh=CwOcsULucec7Oo/4IXsNRVLZDQRHj1jz1tTwxELcAXE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=IiVk2vlQS25ryxBfkwuzMVFWb/4zs4uEIV8ScPf4ZA2KrbTjW59tO+Ik3DS/KsWCH i236+nI5Q864rCK0xbVZgIrnVd4dpmApJRHLMkefl6dGS6o2oSz+4b28YmrWyNwGzx RBcnu00z6JjrhkJaXMi2BbZnw4lsBMC6XXzE08Bg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Chen Cheng , Yu Kuai , Sasha Levin Subject: [PATCH 6.18 0899/1611] md/raid5: use stripe state snapshot in break_stripe_batch_list() Date: Tue, 21 Jul 2026 17:16:55 +0200 Message-ID: <20260721152535.612254893@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152514.750365251@linuxfoundation.org> References: <20260721152514.750365251@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chen Cheng [ Upstream commit 9b249f5ffbeda24c57e6c56ed896c5ca4fc70549 ] The patch just suppress KCSAN noise. No functional change. RAID-5 can group multi full-stripe-write aka stripe_head into a batch aka batch_list, with one head_sh leading them. Call break_stripe_batch_list() when the batch is finished, or, a stripe has to be dropped out of the batch. break_stripe_batch_list() reads stripe state several times while request paths can update thost state words concurrently with lockless bitops, which reported by KCSAN. Use a snapshot to guarantees that the value used for warning, copying, and handle checks is internally consistent at current read moment. KCSAN report: ============================================== BUG: KCSAN: data-race in __add_stripe_bio / break_stripe_batch_list write (marked) to 0xffff8e89d4f0b988 of 8 bytes by task 4323 on cpu 3: __add_stripe_bio+0x35e/0x400 raid5_make_request+0x6ac/0x2930 md_handle_request+0x4a2/0xa40 md_submit_bio+0x109/0x1a0 __submit_bio+0x2ec/0x390 submit_bio_noacct_nocheck+0x457/0x710 submit_bio_noacct+0x2a7/0xc20 submit_bio+0x56/0x250 blkdev_direct_IO+0x54c/0xda0 blkdev_write_iter+0x38f/0x570 aio_write+0x22b/0x490 io_submit_one+0xa51/0xf70 read to 0xffff8e89d4f0b988 of 8 bytes by task 4290 on cpu 4: break_stripe_batch_list+0x3ce/0x480 handle_stripe_clean_event+0x720/0x9b0 handle_stripe+0x32fb/0x4500 handle_active_stripes.isra.0+0x6e0/0xa50 raid5d+0x7e0/0xba0 Signed-off-by: Chen Cheng Link: https://patch.msgid.link/20260618134748.1168360-1-chencheng@fnnas.com Signed-off-by: Yu Kuai Stable-dep-of: 55b77337bdd0 ("md/raid5: avoid R5_Overlap races while breaking stripe batches") Signed-off-by: Sasha Levin --- drivers/md/raid5.c | 45 ++++++++++++++++++++++++++------------------- 1 file changed, 26 insertions(+), 19 deletions(-) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 381f56c4b5e276..e4cbf5fcec8e7a 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -4853,31 +4853,35 @@ static void break_stripe_batch_list(struct stripe_head *head_sh, { struct stripe_head *sh, *next; int i; + unsigned long state; list_for_each_entry_safe(sh, next, &head_sh->batch_list, batch_list) { list_del_init(&sh->batch_list); - WARN_ONCE(sh->state & ((1 << STRIPE_ACTIVE) | - (1 << STRIPE_SYNCING) | - (1 << STRIPE_REPLACED) | - (1 << STRIPE_DELAYED) | - (1 << STRIPE_BIT_DELAY) | - (1 << STRIPE_FULL_WRITE) | - (1 << STRIPE_BIOFILL_RUN) | - (1 << STRIPE_COMPUTE_RUN) | - (1 << STRIPE_DISCARD) | - (1 << STRIPE_BATCH_READY) | - (1 << STRIPE_BATCH_ERR)), - "stripe state: %lx\n", sh->state); - WARN_ONCE(head_sh->state & ((1 << STRIPE_DISCARD) | - (1 << STRIPE_REPLACED)), - "head stripe state: %lx\n", head_sh->state); + state = READ_ONCE(sh->state); + WARN_ONCE(state & ((1 << STRIPE_ACTIVE) | + (1 << STRIPE_SYNCING) | + (1 << STRIPE_REPLACED) | + (1 << STRIPE_DELAYED) | + (1 << STRIPE_BIT_DELAY) | + (1 << STRIPE_FULL_WRITE) | + (1 << STRIPE_BIOFILL_RUN) | + (1 << STRIPE_COMPUTE_RUN) | + (1 << STRIPE_DISCARD) | + (1 << STRIPE_BATCH_READY) | + (1 << STRIPE_BATCH_ERR)), + "stripe state: %lx\n", state); + + state = READ_ONCE(head_sh->state); + WARN_ONCE(state & ((1 << STRIPE_DISCARD) | + (1 << STRIPE_REPLACED)), + "head stripe state: %lx\n", state); set_mask_bits(&sh->state, ~(STRIPE_EXPAND_SYNC_FLAGS | (1 << STRIPE_PREREAD_ACTIVE) | (1 << STRIPE_ON_UNPLUG_LIST)), - head_sh->state & (1 << STRIPE_INSYNC)); + state & (1 << STRIPE_INSYNC)); sh->check_state = head_sh->check_state; sh->reconstruct_state = head_sh->reconstruct_state; @@ -4890,8 +4894,9 @@ static void break_stripe_batch_list(struct stripe_head *head_sh, sh->dev[i].flags = head_sh->dev[i].flags & (~((1 << R5_WriteError) | (1 << R5_Overlap))); } - if (handle_flags == 0 || - sh->state & handle_flags) + + state = READ_ONCE(sh->state); + if (handle_flags == 0 || (state & handle_flags)) set_bit(STRIPE_HANDLE, &sh->state); raid5_release_stripe(sh); } @@ -4901,7 +4906,9 @@ static void break_stripe_batch_list(struct stripe_head *head_sh, for (i = 0; i < head_sh->disks; i++) if (test_and_clear_bit(R5_Overlap, &head_sh->dev[i].flags)) wake_up_bit(&head_sh->dev[i].flags, R5_Overlap); - if (head_sh->state & handle_flags) + + state = READ_ONCE(head_sh->state); + if (state & handle_flags) set_bit(STRIPE_HANDLE, &head_sh->state); } -- 2.53.0