hulk inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I9QJ1S CVE: NA
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Because slow io or io timeout handler can take a long time, hungtask check is forbidden in order to prevent false positive warnings. However, this also cause kenel to be silence if io really hang.
It's quite complicated to distinguish if io is slow or hanged, this patch add a switch to enable hungtask check, the switch is enabled by default, and can be turn off by:
1) disable config BLK_IO_HUNG_TASK_CHECK 2) add blk_core.io_hung_task_check=0 to boot cmd 3) echo 0 > /sys/module/blk_core/parameters/io_hung_task_check
Noted that user has to be careful to use this with hungtask panic enabeld, since there could be false positive hungtask warnings.
Signed-off-by: Yu Kuai yukuai3@huawei.com --- block/Kconfig | 9 +++++++++ block/bio.c | 2 +- block/blk-core.c | 13 ++++++++++++- block/blk-exec.c | 2 +- block/blk.h | 1 + 5 files changed, 24 insertions(+), 3 deletions(-)
diff --git a/block/Kconfig b/block/Kconfig index e5c965f1ea25..e213002d5e73 100644 --- a/block/Kconfig +++ b/block/Kconfig @@ -209,6 +209,15 @@ config BLK_DEV_DUMPINFO Dump info when open an write opened block device exclusively or open an exclusive opened device for write
+config BLK_IO_HUNG_TASK_CHECK + bool "Enable io hung task check" + depends on DETECT_HUNG_TASK + default y + help + Enabling this lets the block layer detect hungtask for io, noted + if this is set, hungtask will complain about slow io even if such + io is not hanged. Be careful to enable hungtask panic in this case. + menu "Partition Types"
source "block/partitions/Kconfig" diff --git a/block/bio.c b/block/bio.c index 8c64c93e96c8..123b44ba17cb 100644 --- a/block/bio.c +++ b/block/bio.c @@ -1169,7 +1169,7 @@ int submit_bio_wait(struct bio *bio) submit_bio(bio);
/* Prevent hang_check timer from firing at us during very long I/O */ - hang_check = sysctl_hung_task_timeout_secs; + hang_check = sysctl_hung_task_timeout_secs && !io_hung_task_check; if (hang_check) while (!wait_for_completion_io_timeout(&done, hang_check * (HZ/2))) diff --git a/block/blk-core.c b/block/blk-core.c index f91f8e8be482..e291ed8ee01e 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -77,6 +77,17 @@ static int __init precise_iostat_setup(char *str) } __setup("precise_iostat=", precise_iostat_setup);
+/* + * Noted if this is set, hungtask will complain about slow io even if such io is + * not hanged. Be careful to enable hungtask panic in this case. + */ +#ifdef CONFIG_BLK_IO_HUNG_TASK_CHECK +bool io_hung_task_check = true; +#else +bool io_hung_task_check; +#endif +module_param_named(io_hung_task_check, io_hung_task_check, bool, 0644); + /* * For queue allocation */ @@ -1879,7 +1890,7 @@ void blk_io_schedule(void) /* Prevent hang_check timer from firing at us during very long I/O */ unsigned long timeout = sysctl_hung_task_timeout_secs * HZ / 2;
- if (timeout) + if (timeout && !io_hung_task_check) io_schedule_timeout(timeout); else io_schedule(); diff --git a/block/blk-exec.c b/block/blk-exec.c index b2676de4c6a5..497aa52cd51e 100644 --- a/block/blk-exec.c +++ b/block/blk-exec.c @@ -87,7 +87,7 @@ blk_status_t blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk, blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq);
/* Prevent hang_check timer from firing at us during very long I/O */ - hang_check = sysctl_hung_task_timeout_secs; + hang_check = sysctl_hung_task_timeout_secs && !io_hung_task_check; if (hang_check) while (!wait_for_completion_io_timeout(&wait, hang_check * (HZ/2))); else diff --git a/block/blk.h b/block/blk.h index 4bbcc971d4f7..2e487673b3a7 100644 --- a/block/blk.h +++ b/block/blk.h @@ -15,6 +15,7 @@ #define BLK_MAX_TIMEOUT (5 * HZ)
extern struct dentry *blk_debugfs_root; +extern bool io_hung_task_check;
struct blk_flush_queue { unsigned int flush_pending_idx:1;