kernel/linux.git/block/blk-throttle.h, branch v6.12.91

blk-throttle: fix access race during throttle policy activation

2026-03-25T10:08:45+00:00

[ Upstream commit bd9fd5be6bc0836820500f68fff144609fbd85a9 ] On repeated cold boots we occasionally hit a NULL pointer crash in blk_should_throtl() when throttling is consulted before the throttle policy is fully enabled for the queue. Checking only q->td != NULL is insufficient during early initialization, so blkg_to_pd() for the throttle policy can still return NULL and blkg_to_tg() becomes NULL, which later gets dereferenced. Unable to handle kernel NULL pointer dereference at virtual address 0000000000000156 ... pc : submit_bio_noacct+0x14c/0x4c8 lr : submit_bio_noacct+0x48/0x4c8 sp : ffff800087f0b690 x29: ffff800087f0b690 x28: 0000000000005f90 x27: ffff00068af393c0 x26: 0000000000080000 x25: 000000000002fbc0 x24: ffff000684ddcc70 x23: 0000000000000000 x22: 0000000000000000 x21: 0000000000000000 x20: 0000000000080000 x19: ffff000684ddcd08 x18: ffffffffffffffff x17: 0000000000000000 x16: ffff80008132a550 x15: 0000ffff98020fff x14: 0000000000000000 x13: 1fffe000d11d7021 x12: ffff000688eb810c x11: ffff00077ec4bb80 x10: ffff000688dcb720 x9 : ffff80008068ef60 x8 : 00000a6fb8a86e85 x7 : 000000000000111e x6 : 0000000000000002 x5 : 0000000000000246 x4 : 0000000000015cff x3 : 0000000000394500 x2 : ffff000682e35e40 x1 : 0000000000364940 x0 : 000000000000001a Call trace: submit_bio_noacct+0x14c/0x4c8 verity_map+0x178/0x2c8 __map_bio+0x228/0x250 dm_submit_bio+0x1c4/0x678 __submit_bio+0x170/0x230 submit_bio_noacct_nocheck+0x16c/0x388 submit_bio_noacct+0x16c/0x4c8 submit_bio+0xb4/0x210 f2fs_submit_read_bio+0x4c/0xf0 f2fs_mpage_readpages+0x3b0/0x5f0 f2fs_readahead+0x90/0xe8 Tighten blk_throtl_activated() to also require that the throttle policy bit is set on the queue: return q->td != NULL && test_bit(blkcg_policy_throtl.plid, q->blkcg_pols); This prevents blk_should_throtl() from accessing throttle group state until policy data has been attached to blkgs. Fixes: a3166c51702b ("blk-throttle: delay initialization until configuration") Co-developed-by: Liang Jie Signed-off-by: Liang Jie Signed-off-by: Han Guangjiang Reviewed-by: Yu Kuai Signed-off-by: Jens Axboe Signed-off-by: Robert Garcia Signed-off-by: Greg Kroah-Hartman

blk-throttle: remove last_low_overflow_time

2024-09-10T22:31:41+00:00

last_low_overflow_time is not used anymore after commit bf20ab538c81 ("blk-throttle: remove CONFIG_BLK_DEV_THROTTLING_LOW"). Signed-off-by: Yu Kuai Acked-by: Tejun Heo Link: https://lore.kernel.org/r/20240903135149.271857-2-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe

blk-throttle: Fix incorrect display of io.max

2024-05-31T01:44:29+00:00

Commit bf20ab538c81 ("blk-throttle: remove CONFIG_BLK_DEV_THROTTLING_LOW") attempts to revert the code change introduced by commit cd5ab1b0fcb4 ("blk-throttle: add .low interface"). However, it leaves behind the bps_conf[] and iops_conf[] fields in the throtl_grp structure which aren't set anywhere in the new blk-throttle.c code but are still being used by tg_prfill_limit() to display the limits in io.max. Now io.max always displays the following values if a block queue is used: : rbps=0 wbps=0 riops=0 wiops=0 Fix this problem by removing bps_conf[] and iops_conf[] and use bps[] and iops[] instead to complete the revert. Fixes: bf20ab538c81 ("blk-throttle: remove CONFIG_BLK_DEV_THROTTLING_LOW") Reported-by: Justin Forbes Closes: https://github.com/containers/podman/issues/22701#issuecomment-2120627789 Signed-off-by: Waiman Long Acked-by: Tejun Heo Reviewed-by: Yu Kuai Link: https://lore.kernel.org/r/20240530134547.970075-1-longman@redhat.com Signed-off-by: Jens Axboe

blk-throttle: delay initialization until configuration

2024-05-09T15:44:56+00:00

Other cgroup policy like bfq, iocost are lazy-initialized when they are configured for the first time for the device, but blk-throttle is initialized unconditionally from blkcg_init_disk(). Delay initialization of blk-throttle as well, to save some cpu and memory overhead if it's not configured. Noted that once it's initialized, it can't be destroyed until disk removal, even if it's disabled. Signed-off-by: Yu Kuai Link: https://lore.kernel.org/r/20240509121107.3195568-3-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe

blk-throttle: remove CONFIG_BLK_DEV_THROTTLING_LOW

2024-05-09T15:44:55+00:00

One the one hand, it's marked EXPERIMENTAL since 2017, and looks like there are no users since then, and no testers and no developers, it's just not active at all. On the other hand, even if the config is disabled, there are still many fields in throtl_grp and throtl_data and many functions that are only used for throtl low. At last, currently blk-throtl is initialized during disk initialization, and destroyed during disk removal, and it exposes many functions to be called directly from block layer. Remove throtl low to make code much more cleaner and follow up work much easier. Signed-off-by: Yu Kuai Acked-by: Tejun Heo Link: https://lore.kernel.org/r/20240509121107.3195568-2-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe

blk-throttle: print signed value 'carryover_bytes/ios' for user

2023-08-30T16:15:01+00:00

'carryover_bytes/ios' can be negative, indicate that some bio is dispatched in advance within slice while configuration is updated. Print a huge value is not user-friendly. Signed-off-by: Yu Kuai Acked-by: Tejun Heo Link: https://lore.kernel.org/r/20230816012708.1193747-2-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe

blk-throttle: Fix io statistics for cgroup v1

2023-06-25T14:00:39+00:00

After commit f382fb0bcef4 ("block: remove legacy IO schedulers"), blkio.throttle.io_serviced and blkio.throttle.io_service_bytes become the only stable io stats interface of cgroup v1, and these statistics are done in the blk-throttle code. But the current code only counts the bios that are actually throttled. When the user does not add the throttle limit, the io stats for cgroup v1 has nothing. I fix it according to the statistical method of v2, and made it count all ios accurately. Fixes: a7b36ee6ba29 ("block: move blk-throtl fast path inline") Tested-by: Andrea Righi Signed-off-by: Jinke Han Acked-by: Muchun Song Acked-by: Tejun Heo Link: https://lore.kernel.org/r/20230507170631.89607-1-hanjinke.666@bytedance.com Signed-off-by: Jens Axboe

blk-throttle: pass a gendisk to blk_throtl_cancel_bios

2022-09-27T01:17:28+00:00

Pass the gendisk to blk_throtl_cancel_bios as part of moving the blk-cgroup infrastructure to be gendisk based. Signed-off-by: Christoph Hellwig Reviewed-by: Andreas Herrmann Acked-by: Tejun Heo Link: https://lore.kernel.org/r/20220921180501.1539876-15-hch@lst.de Signed-off-by: Jens Axboe

blk-throttle: pass a gendisk to blk_throtl_register_queue

2022-09-27T01:17:27+00:00

Pass the gendisk to blk_throtl_register_queue as part of moving the blk-cgroup infrastructure to be gendisk based. Signed-off-by: Christoph Hellwig Reviewed-by: Andreas Herrmann Acked-by: Tejun Heo Link: https://lore.kernel.org/r/20220921180501.1539876-14-hch@lst.de Signed-off-by: Jens Axboe

blk-throttle: pass a gendisk to blk_throtl_init and blk_throtl_exit

2022-09-27T01:17:27+00:00

Pass the gendisk to blk_throtl_init and blk_throtl_exit as part of moving the blk-cgroup infrastructure to be gendisk based. Signed-off-by: Christoph Hellwig Reviewed-by: Andreas Herrmann Acked-by: Tejun Heo Link: https://lore.kernel.org/r/20220921180501.1539876-13-hch@lst.de Signed-off-by: Jens Axboe