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([2a02:3037:621:7039:f080:d03a:2ee1:37d9]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-48a8fee5033sm11797005e9.22.2026.05.01.04.47.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 01 May 2026 04:47:11 -0700 (PDT) From: Abd-Alrhman Masalkhi To: song@kernel.org, yukuai@fnnas.com, xni@redhat.com, neilb@suse.com, shli@fb.com Cc: linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, Abd-Alrhman Masalkhi Subject: [PATCH v2 2/3] md/raid1,raid10: fix error-path detection with md_cloned_bio() Date: Fri, 1 May 2026 13:46:50 +0200 Message-ID: <20260501114652.590037-3-abd.masalkhi@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260501114652.590037-1-abd.masalkhi@gmail.com> References: <20260501114652.590037-1-abd.masalkhi@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Detect the error path using md_cloned_bio() instead of relying on r1_bio in raid1 or r10_bio->read_slot in raid10, which may be NULL or -1 after splitting and resubmitting a failed bio. As a result, the error path may not be recognized and memory allocations can incorrectly use GFP_NOIO instead of (GFP_NOIO | __GFP_HIGH), which can lead to a deadlock under memory pressure. Fixes: 689389a06ce7 ("md/raid1: simplify handle_read_error().") Fixes: 545250f24809 ("md/raid10: simplify handle_read_error()") Signed-off-by: Abd-Alrhman Masalkhi --- This patch depends on patch 1. Changes in v2: - New patch. --- drivers/md/raid1.c | 13 ++++++++++--- drivers/md/raid10.c | 20 ++++++++++++++------ 2 files changed, 24 insertions(+), 9 deletions(-) diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index cc9914bd15c1..c52ecd38c163 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -1321,11 +1321,18 @@ static void raid1_read_request(struct mddev *mddev, struct bio *bio, bool r1bio_existed = !!r1_bio; /* - * If r1_bio is set, we are blocking the raid1d thread - * so there is a tiny risk of deadlock. So ask for + * An md cloned bio indicates we are in the error path. + * This is more reliable than checking r1_bio, which might + * be NULL even in the error path if a failed bio was split. + */ + bool err_path = md_cloned_bio(mddev, bio); + + /* + * If we are in the error path, we are blocking the raid1d + * thread so there is a tiny risk of deadlock. So ask for * emergency memory if needed. */ - gfp_t gfp = r1_bio ? (GFP_NOIO | __GFP_HIGH) : GFP_NOIO; + gfp_t gfp = err_path ? (GFP_NOIO | __GFP_HIGH) : GFP_NOIO; /* * Still need barrier for READ in case that whole diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c index 3a591e60a144..8c6fc398260e 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -1155,7 +1155,20 @@ static void raid10_read_request(struct mddev *mddev, struct bio *bio, char b[BDEVNAME_SIZE]; int slot = r10_bio->read_slot; struct md_rdev *err_rdev = NULL; - gfp_t gfp = GFP_NOIO; + + /* + * An md cloned bio indicates we are in the error path. + * This is more reliable than checking slot, which might + * be -1 even in the error path if a failed bio was split. + */ + bool err_path = md_cloned_bio(mddev, bio); + + /* + * If we are in the error path, we are blocking the raid10d + * thread so there is a tiny risk of deadlock. So ask for + * emergency memory if needed. + */ + gfp_t gfp = err_path ? (GFP_NOIO | __GFP_HIGH) : GFP_NOIO; if (slot >= 0 && r10_bio->devs[slot].rdev) { /* @@ -1166,11 +1179,6 @@ static void raid10_read_request(struct mddev *mddev, struct bio *bio, * we lose the device name in error messages. */ int disk; - /* - * As we are blocking raid10, it is a little safer to - * use __GFP_HIGH. - */ - gfp = GFP_NOIO | __GFP_HIGH; disk = r10_bio->devs[slot].devnum; err_rdev = conf->mirrors[disk].rdev; -- 2.43.0