From: Lee Jones <lee.jones@linaro.org> To: gregkh@google.com Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Mariusz Tkaczyk <mariusz.tkaczyk@intel.com>, Song Liu <songliubraving@fb.com>, Sasha Levin <sashal@kernel.org>, Lee Jones <lee.jones@linaro.org> Subject: [PATCH 07/10] md: fix for divide error in status_resync Date: Thu, 7 Nov 2019 20:16:59 +0000 [thread overview] Message-ID: <20191107201702.27023-7-lee.jones@linaro.org> (raw) In-Reply-To: <20191107201702.27023-1-lee.jones@linaro.org> From: Mariusz Tkaczyk <mariusz.tkaczyk@intel.com> [ Upstream commit 9642fa73d073527b0cbc337cc17a47d545d82cd2 ] Stopping external metadata arrays during resync/recovery causes retries, loop of interrupting and starting reconstruction, until it hit at good moment to stop completely. While these retries curr_mark_cnt can be small- especially on HDD drives, so subtraction result can be smaller than 0. However it is casted to uint without checking. As a result of it the status bar in /proc/mdstat while stopping is strange (it jumps between 0% and 99%). The real problem occurs here after commit 72deb455b5ec ("block: remove CONFIG_LBDAF"). Sector_div() macro has been changed, now the divisor is casted to uint32. For db = -8 the divisior(db/32-1) becomes 0. Check if db value can be really counted and replace these macro by div64_u64() inline. Signed-off-by: Mariusz Tkaczyk <mariusz.tkaczyk@intel.com> Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Lee Jones <lee.jones@linaro.org> Change-Id: If2744cff07135d0c1fa5f55bcec36ab2137b841e --- drivers/md/md.c | 36 ++++++++++++++++++++++-------------- 1 file changed, 22 insertions(+), 14 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index ba201db6afce..9a84a74747f8 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -6701,9 +6701,9 @@ static void status_unused(struct seq_file *seq) static void status_resync(struct seq_file *seq, struct mddev *mddev) { sector_t max_sectors, resync, res; - unsigned long dt, db; - sector_t rt; - int scale; + unsigned long dt, db = 0; + sector_t rt, curr_mark_cnt, resync_mark_cnt; + int scale, recovery_active; unsigned int per_milli; if (mddev->curr_resync <= 3) @@ -6759,22 +6759,30 @@ static void status_resync(struct seq_file *seq, struct mddev *mddev) * db: blocks written from mark until now * rt: remaining time * - * rt is a sector_t, so could be 32bit or 64bit. - * So we divide before multiply in case it is 32bit and close - * to the limit. - * We scale the divisor (db) by 32 to avoid losing precision - * near the end of resync when the number of remaining sectors - * is close to 'db'. - * We then divide rt by 32 after multiplying by db to compensate. - * The '+1' avoids division by zero if db is very small. + * rt is a sector_t, which is always 64bit now. We are keeping + * the original algorithm, but it is not really necessary. + * + * Original algorithm: + * So we divide before multiply in case it is 32bit and close + * to the limit. + * We scale the divisor (db) by 32 to avoid losing precision + * near the end of resync when the number of remaining sectors + * is close to 'db'. + * We then divide rt by 32 after multiplying by db to compensate. + * The '+1' avoids division by zero if db is very small. */ dt = ((jiffies - mddev->resync_mark) / HZ); if (!dt) dt++; - db = (mddev->curr_mark_cnt - atomic_read(&mddev->recovery_active)) - - mddev->resync_mark_cnt; + + curr_mark_cnt = mddev->curr_mark_cnt; + recovery_active = atomic_read(&mddev->recovery_active); + resync_mark_cnt = mddev->resync_mark_cnt; + + if (curr_mark_cnt >= (recovery_active + resync_mark_cnt)) + db = curr_mark_cnt - (recovery_active + resync_mark_cnt); rt = max_sectors - resync; /* number of remaining sectors */ - sector_div(rt, db/32+1); + rt = div64_u64(rt, db/32+1); rt *= dt; rt >>= 5; -- 2.24.0
WARNING: multiple messages have this Message-ID (diff)
From: Lee Jones <lee.jones@linaro.org> To: gregkh@google.com Cc: Sasha Levin <sashal@kernel.org>, Song Liu <songliubraving@fb.com>, linux-kernel@vger.kernel.org, Mariusz Tkaczyk <mariusz.tkaczyk@intel.com>, Lee Jones <lee.jones@linaro.org>, linux-arm-kernel@lists.infradead.org Subject: [PATCH 07/10] md: fix for divide error in status_resync Date: Thu, 7 Nov 2019 20:16:59 +0000 [thread overview] Message-ID: <20191107201702.27023-7-lee.jones@linaro.org> (raw) In-Reply-To: <20191107201702.27023-1-lee.jones@linaro.org> From: Mariusz Tkaczyk <mariusz.tkaczyk@intel.com> [ Upstream commit 9642fa73d073527b0cbc337cc17a47d545d82cd2 ] Stopping external metadata arrays during resync/recovery causes retries, loop of interrupting and starting reconstruction, until it hit at good moment to stop completely. While these retries curr_mark_cnt can be small- especially on HDD drives, so subtraction result can be smaller than 0. However it is casted to uint without checking. As a result of it the status bar in /proc/mdstat while stopping is strange (it jumps between 0% and 99%). The real problem occurs here after commit 72deb455b5ec ("block: remove CONFIG_LBDAF"). Sector_div() macro has been changed, now the divisor is casted to uint32. For db = -8 the divisior(db/32-1) becomes 0. Check if db value can be really counted and replace these macro by div64_u64() inline. Signed-off-by: Mariusz Tkaczyk <mariusz.tkaczyk@intel.com> Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Lee Jones <lee.jones@linaro.org> Change-Id: If2744cff07135d0c1fa5f55bcec36ab2137b841e --- drivers/md/md.c | 36 ++++++++++++++++++++++-------------- 1 file changed, 22 insertions(+), 14 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index ba201db6afce..9a84a74747f8 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -6701,9 +6701,9 @@ static void status_unused(struct seq_file *seq) static void status_resync(struct seq_file *seq, struct mddev *mddev) { sector_t max_sectors, resync, res; - unsigned long dt, db; - sector_t rt; - int scale; + unsigned long dt, db = 0; + sector_t rt, curr_mark_cnt, resync_mark_cnt; + int scale, recovery_active; unsigned int per_milli; if (mddev->curr_resync <= 3) @@ -6759,22 +6759,30 @@ static void status_resync(struct seq_file *seq, struct mddev *mddev) * db: blocks written from mark until now * rt: remaining time * - * rt is a sector_t, so could be 32bit or 64bit. - * So we divide before multiply in case it is 32bit and close - * to the limit. - * We scale the divisor (db) by 32 to avoid losing precision - * near the end of resync when the number of remaining sectors - * is close to 'db'. - * We then divide rt by 32 after multiplying by db to compensate. - * The '+1' avoids division by zero if db is very small. + * rt is a sector_t, which is always 64bit now. We are keeping + * the original algorithm, but it is not really necessary. + * + * Original algorithm: + * So we divide before multiply in case it is 32bit and close + * to the limit. + * We scale the divisor (db) by 32 to avoid losing precision + * near the end of resync when the number of remaining sectors + * is close to 'db'. + * We then divide rt by 32 after multiplying by db to compensate. + * The '+1' avoids division by zero if db is very small. */ dt = ((jiffies - mddev->resync_mark) / HZ); if (!dt) dt++; - db = (mddev->curr_mark_cnt - atomic_read(&mddev->recovery_active)) - - mddev->resync_mark_cnt; + + curr_mark_cnt = mddev->curr_mark_cnt; + recovery_active = atomic_read(&mddev->recovery_active); + resync_mark_cnt = mddev->resync_mark_cnt; + + if (curr_mark_cnt >= (recovery_active + resync_mark_cnt)) + db = curr_mark_cnt - (recovery_active + resync_mark_cnt); rt = max_sectors - resync; /* number of remaining sectors */ - sector_div(rt, db/32+1); + rt = div64_u64(rt, db/32+1); rt *= dt; rt >>= 5; -- 2.24.0 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-11-07 20:17 UTC|newest] Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-11-07 20:16 [PATCH 01/10] ASoC: max98090: remove 24-bit format support if RJ is 0 Lee Jones 2019-11-07 20:16 ` Lee Jones 2019-11-07 20:16 ` [PATCH 02/10] usb: gadget: udc: lpc32xx: allocate descriptor with GFP_ATOMIC Lee Jones 2019-11-07 20:16 ` Lee Jones 2019-11-07 20:16 ` [PATCH 03/10] mac80211: mesh: fix RCU warning Lee Jones 2019-11-07 20:16 ` Lee Jones 2019-11-07 20:16 ` [PATCH 04/10] mwifiex: Abort at too short BSS descriptor element Lee Jones 2019-11-07 20:16 ` Lee Jones 2019-11-07 20:16 ` [PATCH 05/10] Input: imx_keypad - make sure keyboard can always wake up system Lee Jones 2019-11-07 20:16 ` Lee Jones 2019-11-07 20:16 ` [PATCH 06/10] ARM: davinci: da850-evm: call regulator_has_full_constraints() Lee Jones 2019-11-07 20:16 ` Lee Jones 2019-11-07 20:16 ` Lee Jones [this message] 2019-11-07 20:16 ` [PATCH 07/10] md: fix for divide error in status_resync Lee Jones 2019-11-07 20:17 ` [PATCH 08/10] bnx2x: Check if transceiver implements DDM before access Lee Jones 2019-11-07 20:17 ` Lee Jones 2019-11-07 20:17 ` [PATCH 09/10] ARM: davinci: da8xx: specify dma_coherent_mask for lcdc Lee Jones 2019-11-07 20:17 ` Lee Jones 2019-11-07 20:17 ` [PATCH 10/10] can: mcp251x: add support for mcp25625 Lee Jones 2019-11-07 20:17 ` Lee Jones 2019-11-08 7:42 ` [PATCH 01/10] ASoC: max98090: remove 24-bit format support if RJ is 0 Lee Jones 2019-11-08 7:42 ` Lee Jones
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20191107201702.27023-7-lee.jones@linaro.org \ --to=lee.jones@linaro.org \ --cc=gregkh@google.com \ --cc=linux-arm-kernel@lists.infradead.org \ --cc=linux-kernel@vger.kernel.org \ --cc=mariusz.tkaczyk@intel.com \ --cc=sashal@kernel.org \ --cc=songliubraving@fb.com \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.