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2025-05-06block: don't allow to switch elevator if updating nr_hw_queues is in-progressMing Lei
Elevator switch code is another `nr_hw_queue` reader in non-fast-IO code path, so it can't be done if updating `nr_hw_queues` is in-progress. Take same approach with not allowing add/del disk when updating nr_hw_queues is in-progress, by grabbing read lock of set->update_nr_hwq_sema. Reviewed-by: Hannes Reinecke <hare@suse.de> Link: https://lore.kernel.org/linux-block/aAWv3NPtNIKKvJZc@fedora/ [1] Reported-by: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com> Closes: https://lore.kernel.org/linux-block/mz4t4tlwiqjijw3zvqnjb7ovvvaegkqganegmmlc567tt5xj67@xal5ro544cnc/ Signed-off-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Nilay Shroff <nilay@linux.ibm.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20250505141805.2751237-10-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-05-06block: prevent adding/deleting disk during updating nr_hw_queuesMing Lei
Both adding/deleting disk code are reader of `nr_hw_queues`, so we can't allow them in-progress when updating nr_hw_queues, kernel panic and kasan has been reported in [1]. Prevent adding/deleting disk during updating nr_hw_queues by adding rw_semaphore to tagset, write lock is grabbed in blk_mq_update_nr_hw_queues(), and read lock is acquired when adding/deleting disk. Also mark GFP_NOIO allocation scope for adding/deleting disk because blk_mq_update_nr_hw_queues() is part of some driver's error handler. This way avoids lot of trouble. Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Nilay Shroff <nilay@linux.ibm.com> Suggested-by: Nilay Shroff <nilay@linux.ibm.com> Reported-by: Nilay Shroff <nilay@linux.ibm.com> Closes: https://lore.kernel.org/linux-block/a5896cdb-a59a-4a37-9f99-20522f5d2987@linux.ibm.com/ Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20250505141805.2751237-9-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-05-06block: add helper add_disk_final()Ming Lei
Add helper add_disk_final() for scanning partitions, announcing disk and handling the last thing for adding disk. No functional change, and prepare for prevent adding disk from happening when updating nr_hw_queues. Signed-off-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Nilay Shroff <nilay@linux.ibm.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20250505141805.2751237-8-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-05-06block: move sched debugfs register into elvevator_register_queueMing Lei
sched debugfs shares same lifetime with scheduler's kobject, and same lock(elevator lock), so move sched debugfs register/unregister into elevator_register_queue() and elevator_unregister_queue(). Then we needn't blk_mq_debugfs_register() for us to register sched debugfs any more. Reviewed-by: Yu Kuai <yukuai3@huawei.com> Reviewed-by: Nilay Shroff <nilay@linux.ibm.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20250505141805.2751237-7-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-05-06block: add two helpers for registering/un-registering sched debugfsMing Lei
Add blk_mq_sched_reg_debugfs()/blk_mq_sched_unreg_debugfs() to clean up sched init/exit code a bit. Register & unregister debugfs for sched & sched_hctx order is changed a bit, but it is safe because sched & sched_hctx is guaranteed to be ready when exporting via debugfs. Reviewed-by: Yu Kuai <yukuai3@huawei.com> Reviewed-by: Nilay Shroff <nilay@linux.ibm.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20250505141805.2751237-6-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-05-06block: use q->elevator with ->elevator_lock held in elv_iosched_show()Ming Lei
Use q->elevator with ->elevator_lock held in elv_iosched_show(), since the local cached elevator reference may become stale after getting ->elevator_lock. Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Nilay Shroff <nilay@linux.ibm.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20250505141805.2751237-5-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-05-06block: don't call freeze queue in elevator_switch() and elevator_disable()Ming Lei
Both elevator_switch() and elevator_disable() are only called from the two code paths, in which queue is guaranteed to be frozen. So don't call freeze queue in the two functions, also add asserts for queue freeze. Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Nilay Shroff <nilay@linux.ibm.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Yu Kuai <yukuai3@huawei.com> Link: https://lore.kernel.org/r/20250505141805.2751237-4-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-05-06block: move ELEVATOR_FLAG_DISABLE_WBT a request queue flagMing Lei
ELEVATOR_FLAG_DISABLE_WBT is only used by BFQ to disallow wbt when BFQ is in use. The flag is set in BFQ's init(), and cleared in BFQ's exit(). Making it as request queue flag, so that we can avoid to deal with elevator switch race. Also it isn't graceful to checking one scheduler flag in wbt_enable_default(). Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Nilay Shroff <nilay@linux.ibm.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20250505141805.2751237-3-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-05-06block: move blk_mq_add_queue_tag_set() after blk_mq_map_swqueue()Ming Lei
Move blk_mq_add_queue_tag_set() after blk_mq_map_swqueue(), and publish this request queue to tagset after everything is setup. This way is safe because BLK_MQ_F_TAG_QUEUE_SHARED isn't used by blk_mq_map_swqueue(), and this flag is mainly checked in fast IO code path. Prepare for removing ->elevator_lock from blk_mq_map_swqueue() which is supposed to be called when elevator switch can't be done. Reviewed-by: Nilay Shroff <nilay@linux.ibm.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Reported-by: Nilay Shroff <nilay@linux.ibm.com> Closes: https://lore.kernel.org/linux-block/567cb7ab-23d6-4cee-a915-c8cdac903ddd@linux.ibm.com/ Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20250505141805.2751237-2-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-05-05blk-throttle: Add an additional overflow check to the call ↵Zizhi Wo
calculate_bytes/io_allowed Now the tg->[bytes/io]_disp type is signed, and calculate_bytes/io_allowed return type is unsigned. Even if the bps/iops limit is not set to max, the return value of the function may still exceed INT_MAX or LLONG_MAX, which can cause overflow in outer variables. In such cases, we can add additional checks accordingly. And in throtl_trim_slice(), if the BPS/IOPS limit is set to max, there's no need to call calculate_bytes/io_allowed(). Introduces the helper functions throtl_trim_bps/iops to simplifies the process. For cases when the calculated trim value exceeds INT_MAX (causing an overflow), we reset tg->[bytes/io]_disp to zero, so return original tg->[bytes/io]_disp because it is the size that is actually trimmed. Signed-off-by: Zizhi Wo <wozizhi@huawei.com> Reviewed-by: Yu Kuai <yukuai3@huawei.com> Link: https://lore.kernel.org/r/20250417132054.2866409-4-wozizhi@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-05-05blk-throttle: Delete unnecessary carryover-related fields from throtl_grpZizhi Wo
We no longer need carryover_[bytes/ios] in tg, so it is removed. The related comments about carryover in tg are also merged into [bytes/io]_disp, and modify other related comments. Signed-off-by: Zizhi Wo <wozizhi@huawei.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Yu Kuai <yukuai3@huawei.com> Link: https://lore.kernel.org/r/20250417132054.2866409-3-wozizhi@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-05-05blk-throttle: Fix wrong tg->[bytes/io]_disp update in __tg_update_carryover()Zizhi Wo
In commit 6cc477c36875 ("blk-throttle: carry over directly"), the carryover bytes/ios was be carried to [bytes/io]_disp. However, its update mechanism has some issues. In __tg_update_carryover(), we calculate "bytes" and "ios" to represent the carryover, but the computation when updating [bytes/io]_disp is incorrect. And if the sq->nr_queued is empty, we may not update tg->[bytes/io]_disp to 0 in tg_update_carryover(). We should set it to 0 in non carryover case. This patch fixes the issue. Fixes: 6cc477c36875 ("blk-throttle: carry over directly") Signed-off-by: Zizhi Wo <wozizhi@huawei.com> Reviewed-by: Yu Kuai <yukuai3@huawei.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20250417132054.2866409-2-wozizhi@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-05-05block: remove bounce buffering supportChristoph Hellwig
The block layer bounce buffering support is unused now, remove it. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: John Garry <john.g.garry@oracle.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Link: https://lore.kernel.org/r/20250505081138.3435992-7-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-05-02block: use writeback_iterChristoph Hellwig
Use writeback_iter instead of the deprecated write_cache_pages wrapper in blkdev_writepages. This removes an indirect call per folio. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: John Garry <john.g.garry@oracle.com> Link: https://lore.kernel.org/r/20250424082752.1967679-1-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-05-02block: avoid hctx spinlock for plug with multiple queuesCaleb Sander Mateos
blk_mq_flush_plug_list() has a fast path if all requests in the plug are destined for the same request_queue. It calls ->queue_rqs() with the whole batch of requests, falling back on ->queue_rq() for any requests not handled by ->queue_rqs(). However, if the requests are destined for multiple queues, blk_mq_flush_plug_list() has a slow path that calls blk_mq_dispatch_list() repeatedly to filter the requests by ctx/hctx. Each queue's requests are inserted into the hctx's dispatch list under a spinlock, then __blk_mq_sched_dispatch_requests() takes them out of the dispatch list (taking the spinlock again), and finally blk_mq_dispatch_rq_list() calls ->queue_rq() on each request. Acquiring the hctx spinlock twice and calling ->queue_rq() instead of ->queue_rqs() makes the slow path significantly more expensive. Thus, batching more requests into a single plug (e.g. io_uring_enter syscall) can counterintuitively hurt performance by causing the plug to span multiple queues. We have observed 2-3% of CPU time spent acquiring the hctx spinlock alone on workloads issuing requests to multiple NVMe devices in the same io_uring SQE batches. Add a medium path in blk_mq_flush_plug_list() for plugs that don't have elevators or come from a schedule, but do span multiple queues. Filter the requests by queue and call ->queue_rqs()/->queue_rq() on the list of requests destined to each request_queue. With this change, we no longer see any CPU time spent in _raw_spin_lock from blk_mq_flush_plug_list and throughput increases accordingly. Signed-off-by: Caleb Sander Mateos <csander@purestorage.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20250426011728.4189119-4-csander@purestorage.com [axboe: fix whitespace damage] Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-05-02block: factor out blk_mq_dispatch_queue_requests() helperCaleb Sander Mateos
Factor out the logic from blk_mq_flush_plug_list() that calls ->queue_rqs() with a fallback to ->queue_rq() into a helper function blk_mq_dispatch_queue_requests(). This is in preparation for using this code with other lists of requests. Signed-off-by: Caleb Sander Mateos <csander@purestorage.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20250426011728.4189119-3-csander@purestorage.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-05-02block: take rq_list instead of plug in dispatch functionsCaleb Sander Mateos
blk_mq_plug_issue_direct(), __blk_mq_flush_plug_list(), and blk_mq_dispatch_plug_list() take a struct blk_plug * but only use its mq_list. Pass the struct rq_list * instead in preparation for calling them with other lists of requests. Drop "plug" from the function names as they are no longer plug-specific. Signed-off-by: Caleb Sander Mateos <csander@purestorage.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20250426011728.4189119-2-csander@purestorage.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-04-28Merge remote-tracking branch 'linux-block/block-6.15' into xfs treeCarlos Maiolino
We need two patches inside linux-block tree as dependencies of the patch which will follow this merge. Specifically, we need: block: fix race between set_blocksize and read paths block: hoist block size validation code to a separate function Signed-off-by: Carlos Maiolino <cem@kernel.org>
2025-04-25Merge tag 'block-6.15-20250424' of git://git.kernel.dk/linuxLinus Torvalds
Pull block fixes from Jens Axboe: - Fix autoloading of drivers from stat*(2) - Fix losing read-ahead setting one suspend/resume, when a device is re-probed. - Fix race between setting the block size and page cache updates. Includes a helper that a coming XFS fix will use as well. - ublk cancelation fixes. - ublk selftest additions and fixes. - NVMe pull via Christoph: - fix an out-of-bounds access in nvmet_enable_port (Richard Weinberger) * tag 'block-6.15-20250424' of git://git.kernel.dk/linux: ublk: fix race between io_uring_cmd_complete_in_task and ublk_cancel_cmd ublk: call ublk_dispatch_req() for handling UBLK_U_IO_NEED_GET_DATA block: don't autoload drivers on blk-cgroup configuration block: don't autoload drivers on stat block: remove the backing_inode variable in bdev_statx block: move blkdev_{get,put} _no_open prototypes out of blkdev.h block: never reduce ra_pages in blk_apply_bdi_limits selftests: ublk: common: fix _get_disk_dev_t for pre-9.0 coreutils selftests: ublk: remove useless 'delay_us' from 'struct dev_ctx' selftests: ublk: fix recover test block: hoist block size validation code to a separate function block: fix race between set_blocksize and read paths nvmet: fix out-of-bounds access in nvmet_enable_port
2025-04-24Merge branch 'block-6.15' into for-6.16/blockJens Axboe
Merge 6.15 block fixes - both to get the fixes causing issues with XFS testing, but also to make it easier for 6.16 ublk patches to avoid conflicts. * block-6.15: ublk: fix race between io_uring_cmd_complete_in_task and ublk_cancel_cmd ublk: call ublk_dispatch_req() for handling UBLK_U_IO_NEED_GET_DATA block: don't autoload drivers on blk-cgroup configuration block: don't autoload drivers on stat block: remove the backing_inode variable in bdev_statx block: move blkdev_{get,put} _no_open prototypes out of blkdev.h block: never reduce ra_pages in blk_apply_bdi_limits selftests: ublk: common: fix _get_disk_dev_t for pre-9.0 coreutils selftests: ublk: remove useless 'delay_us' from 'struct dev_ctx' selftests: ublk: fix recover test block: hoist block size validation code to a separate function block: fix race between set_blocksize and read paths nvmet: fix out-of-bounds access in nvmet_enable_port
2025-04-24block: don't autoload drivers on blk-cgroup configurationChristoph Hellwig
Loading a driver just to configure blk-cgroup doesn't make sense, as that assumes and already existing device. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Christian Brauner <brauner@kernel.org> Acked-by: Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/r/20250423053810.1683309-5-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-04-24block: don't autoload drivers on statChristoph Hellwig
blkdev_get_no_open can trigger the legacy autoload of block drivers. A simple stat of a block device has not historically done that, so disable this behavior again. Fixes: 9abcfbd235f5 ("block: Add atomic write support for statx") Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Christian Brauner <brauner@kernel.org> Acked-by: Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/r/20250423053810.1683309-4-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-04-24block: remove the backing_inode variable in bdev_statxChristoph Hellwig
backing_inode is only used once, so remove it and update the comment describing the bdev lookup to be a bit more clear. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Christian Brauner <brauner@kernel.org> Acked-by: Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/r/20250423053810.1683309-3-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-04-24block: move blkdev_{get,put} _no_open prototypes out of blkdev.hChristoph Hellwig
These are only to be used by block internal code. Remove the comment as we grew more users due to reworking block device node opening. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Christian Brauner <brauner@kernel.org> Acked-by: Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/r/20250423053810.1683309-2-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-04-24block: never reduce ra_pages in blk_apply_bdi_limitsChristoph Hellwig
When the user increased the read-ahead size through sysfs this value currently get lost if the device is reprobe, including on a resume from suspend. As there is no hardware limitation for the read-ahead size there is no real need to reset it or track a separate hardware limitation like for max_sectors. This restores the pre-atomic queue limit behavior in the sd driver as sd did not use blk_queue_io_opt and thus never updated the read ahead size to the value based of the optimal I/O, but changes behavior for all other drivers. As the new behavior seems useful and sd is the driver for which the readahead size tweaks are most useful that seems like a worthwhile trade off. Fixes: 804e498e0496 ("sd: convert to the atomic queue limits API") Reported-by: Holger Hoffstätte <holger@applied-asynchrony.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Link: https://lore.kernel.org/r/20250424082521.1967286-1-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-04-23block: hoist block size validation code to a separate functionDarrick J. Wong
Hoist the block size validation code to bdev_validate_blocksize so that we can call it from filesystems that don't care about the bdev pagecache manipulations of set_blocksize. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/174543795720.4139148.840349813093799165.stgit@frogsfrogsfrogs Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-04-23block: fix race between set_blocksize and read pathsDarrick J. Wong
With the new large sector size support, it's now the case that set_blocksize can change i_blksize and the folio order in a manner that conflicts with a concurrent reader and causes a kernel crash. Specifically, let's say that udev-worker calls libblkid to detect the labels on a block device. The read call can create an order-0 folio to read the first 4096 bytes from the disk. But then udev is preempted. Next, someone tries to mount an 8k-sectorsize filesystem from the same block device. The filesystem calls set_blksize, which sets i_blksize to 8192 and the minimum folio order to 1. Now udev resumes, still holding the order-0 folio it allocated. It then tries to schedule a read bio and do_mpage_readahead tries to create bufferheads for the folio. Unfortunately, blocks_per_folio == 0 because the page size is 4096 but the blocksize is 8192 so no bufferheads are attached and the bh walk never sets bdev. We then submit the bio with a NULL block device and crash. Therefore, truncate the page cache after flushing but before updating i_blksize. However, that's not enough -- we also need to lock out file IO and page faults during the update. Take both the i_rwsem and the invalidate_lock in exclusive mode for invalidations, and in shared mode for read/write operations. I don't know if this is the correct fix, but xfs/259 found it. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com> Link: https://lore.kernel.org/r/174543795699.4139148.2086129139322431423.stgit@frogsfrogsfrogs Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-04-21block: blk-rq-qos: guard rq-qos helpers by static keyJens Axboe
Even if blk-rq-qos isn't used or configured, dipping into the queue to fetch ->rq_qos is a noticeable slowdown and visible in profiles. Add an unlikely static key around blk-rq-qos, to avoid fetching this cacheline if blk-iolatency or blk-wbt isn't configured or used. Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-04-21block: ensure that struct blk_mq_alloc_data is fully initializedJens Axboe
On x86, rep stos will be emitted to clear the the blk_mq_alloc_data struct, as not all members are being explicitly initialied. Depending on the type of CPU, this is a noticeable slowdown compared to just ensuring that the struct is fully initialized when setup. For the 4 spots that setup a struct blk_mq_alloc_data on the stack, ensure all members are being initialized. Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-04-21block: Simplify blk_mq_dispatch_rq_list() and its callersBart Van Assche
The 'nr_budgets' argument of blk_mq_dispatch_rq_list() is either the number of elements in the 'list' argument or zero. Instead of passing the number of list elements to blk_mq_dispatch_rq_list(), pass a boolean argument that indicates whether or not blk_mq_dispatch_rq_list() should request the block driver for a budget for each request in 'list'. Remove the code for counting list elements from blk_mq_dispatch_rq_list() callers where possible. Remove the code that decrements nr_budgets from blk_mq_dispatch_rq_list() because it is superfluous. Each request that is processed by blk_mq_dispatch_rq_list() is in one of these two states if 'get_budget' is false: * Either the request is on 'list' and the budget for the request has to be released from the error path. * Or the request is not on 'list' and q->mq_ops->queue_rq() has already released the budget (ret != BLK_STS_OK) or q->mq_ops->queue_rq() will release the budget asynchronously (ret == BLK_STS_OK). Cc: Christoph Hellwig <hch@lst.de> Cc: Ming Lei <ming.lei@redhat.com> Cc: John Garry <john.g.garry@oracle.com> Signed-off-by: Bart Van Assche <bvanassche@acm.org> Link: https://lore.kernel.org/r/20250415205134.3650042-1-bvanassche@acm.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-04-19Merge tag 'vfs-6.15-rc3.fixes.2' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs Pull vfs fixes from Christian Brauner: - Revert the hfs{plus} deprecation warning that's also included in this pull request. The commit introducing the deprecation warning resides rather early in this branch. So simply dropping it would've rebased all other commits which I decided to avoid. Hence the revert in the same branch [ Background - the deprecation warning discussion resulted in people stepping up, and so hfs{plus} will have a maintainer taking care of it after all.. - Linus ] - Switch CONFIG_SYSFS_SYCALL default to n and decouple from CONFIG_EXPERT - Fix an audit bug caused by changes to our kernel path lookup helpers this cycle. Audit needs the parent path even if the dentry it tried to look up is negative - Ensure that the kernel path lookup helpers leave the passed in path argument clean when they return an error. This is consistent with all our other helpers - Ensure that vfs_getattr_nosec() calls bdev_statx() so the relevant information is available to kernel consumers as well - Don't set a timer and call schedule() if the timer will expire immediately in epoll - Make netfs lookup tables with __nonstring * tag 'vfs-6.15-rc3.fixes.2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: Revert "hfs{plus}: add deprecation warning" fs: move the bdex_statx call to vfs_getattr_nosec netfs: Mark __nonstring lookup tables eventpoll: Set epoll timeout if it's in the future fs: ensure that *path_locked*() helpers leave passed path pristine fs: add kern_path_locked_negative() hfs{plus}: add deprecation warning Kconfig: switch CONFIG_SYSFS_SYCALL default to n
2025-04-18Merge tag 'block-6.15-20250417' of git://git.kernel.dk/linuxLinus Torvalds
Pull block fixes from Jens Axboe: - MD pull via Yu: - fix raid10 missing discard IO accounting (Yu Kuai) - fix bitmap stats for bitmap file (Zheng Qixing) - fix oops while reading all member disks failed during check/repair (Meir Elisha) - NVMe pull via Christoph: - fix scan failure for non-ANA multipath controllers (Hannes Reinecke) - fix multipath sysfs links creation for some cases (Hannes Reinecke) - PCIe endpoint fixes (Damien Le Moal) - use NULL instead of 0 in the auth code (Damien Le Moal) - Various ublk fixes: - Slew of selftest additions - Improvements and fixes for IO cancelation - Tweak to Kconfig verbiage - Fix for page dirtying for blk integrity mapped pages - loop fixes: - buffered IO fix - uevent fixes - request priority inheritance fix - Various little fixes * tag 'block-6.15-20250417' of git://git.kernel.dk/linux: (38 commits) selftests: ublk: add generic_06 for covering fault inject ublk: simplify aborting ublk request ublk: remove __ublk_quiesce_dev() ublk: improve detection and handling of ublk server exit ublk: move device reset into ublk_ch_release() ublk: rely on ->canceling for dealing with ublk_nosrv_dev_should_queue_io ublk: add ublk_force_abort_dev() ublk: properly serialize all FETCH_REQs selftests: ublk: move creating UBLK_TMP into _prep_test() selftests: ublk: add test_stress_05.sh selftests: ublk: support user recovery selftests: ublk: support target specific command line selftests: ublk: increase max nr_queues and queue depth selftests: ublk: set queue pthread's cpu affinity selftests: ublk: setup ring with IORING_SETUP_SINGLE_ISSUER/IORING_SETUP_DEFER_TASKRUN selftests: ublk: add two stress tests for zero copy feature selftests: ublk: run stress tests in parallel selftests: ublk: make sure _add_ublk_dev can return in sub-shell selftests: ublk: cleanup backfile automatically selftests: ublk: add io_uring uapi header ...
2025-04-17fs: move the bdex_statx call to vfs_getattr_nosecChristoph Hellwig
Currently bdex_statx is only called from the very high-level vfs_statx_path function, and thus bypassing it for in-kernel calls to vfs_getattr or vfs_getattr_nosec. This breaks querying the block ѕize of the underlying device in the loop driver and also is a pitfall for any other new kernel caller. Move the call into the lowest level helper to ensure all callers get the right results. Fixes: 2d985f8c6b91 ("vfs: support STATX_DIOALIGN on block devices") Fixes: f4774e92aab8 ("loop: take the file system minimum dio alignment into account") Reported-by: "Darrick J. Wong" <djwong@kernel.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/20250417064042.712140-1-hch@lst.de Signed-off-by: Christian Brauner <brauner@kernel.org>
2025-04-16block: integrity: Do not call set_page_dirty_lock()Martin K. Petersen
Placing multiple protection information buffers inside the same page can lead to oopses because set_page_dirty_lock() can't be called from interrupt context. Since a protection information buffer is not backed by a file there is no point in setting its page dirty, there is nothing to synchronize. Drop the call to set_page_dirty_lock() and remove the last argument to bio_integrity_unpin_bvec(). Cc: stable@vger.kernel.org Fixes: 492c5d455969 ("block: bio-integrity: directly map user buffers") Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Keith Busch <kbusch@kernel.org> Link: https://lore.kernel.org/r/yq1v7r3ev9g.fsf@ca-mkp.ca.oracle.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-04-14block: fix resource leak in blk_register_queue() error pathZheng Qixing
When registering a queue fails after blk_mq_sysfs_register() is successful but the function later encounters an error, we need to clean up the blk_mq_sysfs resources. Add the missing blk_mq_sysfs_unregister() call in the error path to properly clean up these resources and prevent a memory leak. Fixes: 320ae51feed5 ("blk-mq: new multi-queue block IO queueing mechanism") Signed-off-by: Zheng Qixing <zhengqixing@huawei.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Yu Kuai <yukuai3@huawei.com> Link: https://lore.kernel.org/r/20250412092554.475218-1-zhengqixing@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-04-14block: add SPDX header line to blk-throttle.hBird, Tim
Add an SPDX license identifier line to blk-throttle.h Use 'GPL-2.0' as the identifier, since blk-throttle.c uses that, and blk.h (from which some material was copied when blk-throttle.h was created) also uses that identifier. Signed-off-by: Tim Bird <tim.bird@sony.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/MW5PR13MB5632EE4645BCA24ED111EC0EFDB62@MW5PR13MB5632.namprd13.prod.outlook.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-04-07mm: Remove swap_writepage() and shmem_writepage()Matthew Wilcox (Oracle)
Call swap_writeout() and shmem_writeout() from pageout() instead. Signed-off-by: "Matthew Wilcox (Oracle)" <willy@infradead.org> Link: https://lore.kernel.org/r/20250402150005.2309458-9-willy@infradead.org Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> Signed-off-by: Christian Brauner <brauner@kernel.org>
2025-04-05treewide: Switch/rename to timer_delete[_sync]()Thomas Gleixner
timer_delete[_sync]() replaces del_timer[_sync](). Convert the whole tree over and remove the historical wrapper inlines. Conversion was done with coccinelle plus manual fixups where necessary. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2025-04-04cgroup: change rstat function signatures from cgroup-based to css-basedJP Kobryn
This non-functional change serves as preparation for moving to subsystem-based rstat trees. To simplify future commits, change the signatures of existing cgroup-based rstat functions to become css-based and rename them to reflect that. Though the signatures have changed, the implementations have not. Within these functions use the css->cgroup pointer to obtain the associated cgroup and allow code to function the same just as it did before this patch. At applicable call sites, pass the subsystem-specific css pointer as an argument or pass a pointer to cgroup::self if not in subsystem context. Note that cgroup_rstat_updated_list() and cgroup_rstat_push_children() are not altered yet since there would be a larger amount of css to cgroup conversions which may overcomplicate the code at this intermediate phase. Signed-off-by: JP Kobryn <inwardvessel@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2025-04-03block: don't grab elevator lock during queue initializationMing Lei
->elevator_lock depends on queue freeze lock, see block/blk-sysfs.c. queue freeze lock depends on fs_reclaim. So don't grab elevator lock during queue initialization which needs to call kmalloc(GFP_KERNEL), and we can cut the dependency between ->elevator_lock and fs_reclaim, then the lockdep warning can be killed. This way is safe because elevator setting isn't ready to run during queue initialization. There isn't such issue in __blk_mq_update_nr_hw_queues() because memalloc_noio_save() is called before acquiring elevator lock. Fixes the following lockdep warning: https://lore.kernel.org/linux-block/67e6b425.050a0220.2f068f.007b.GAE@google.com/ Reported-by: syzbot+4c7e0f9b94ad65811efb@syzkaller.appspotmail.com Cc: Nilay Shroff <nilay@linux.ibm.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20250403105402.1334206-1-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-04-01block: remove unused nseg parameterNitesh Shetty
We are no longer using nr_segs, after blk_mq_attempt_bio_merge was moved out of blk_mq_get_new_request. Signed-off-by: Nitesh Shetty <nj.shetty@samsung.com> Link: https://lore.kernel.org/r/20250401044348.15588-1-nj.shetty@samsung.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-03-26Merge tag 'for-6.15/block-20250322' of git://git.kernel.dk/linuxLinus Torvalds
Pull block updates from Jens Axboe: - Fixes for integrity handling - NVMe pull request via Keith: - Secure concatenation for TCP transport (Hannes) - Multipath sysfs visibility (Nilay) - Various cleanups (Qasim, Baruch, Wang, Chen, Mike, Damien, Li) - Correct use of 64-bit BARs for pci-epf target (Niklas) - Socket fix for selinux when used in containers (Peijie) - MD pull request via Yu: - fix recovery can preempt resync (Li Nan) - fix md-bitmap IO limit (Su Yue) - fix raid10 discard with REQ_NOWAIT (Xiao Ni) - fix raid1 memory leak (Zheng Qixing) - fix mddev uaf (Yu Kuai) - fix raid1,raid10 IO flags (Yu Kuai) - some refactor and cleanup (Yu Kuai) - Series cleaning up and fixing bugs in the bad block handling code - Improve support for write failure simulation in null_blk - Various lock ordering fixes - Fixes for locking for debugfs attributes - Various ublk related fixes and improvements - Cleanups for blk-rq-qos wait handling - blk-throttle fixes - Fixes for loop dio and sync handling - Fixes and cleanups for the auto-PI code - Block side support for hardware encryption keys in blk-crypto - Various cleanups and fixes * tag 'for-6.15/block-20250322' of git://git.kernel.dk/linux: (105 commits) nvmet: replace max(a, min(b, c)) by clamp(val, lo, hi) nvme-tcp: fix selinux denied when calling sock_sendmsg nvmet: pci-epf: Always configure BAR0 as 64-bit nvmet: Remove duplicate uuid_copy nvme: zns: Simplify nvme_zone_parse_entry() nvmet: pci-epf: Remove redundant 'flush_workqueue()' calls nvmet-fc: Remove unused functions nvme-pci: remove stale comment nvme-fc: Utilise min3() to simplify queue count calculation nvme-multipath: Add visibility for queue-depth io-policy nvme-multipath: Add visibility for numa io-policy nvme-multipath: Add visibility for round-robin io-policy nvmet: add tls_concat and tls_key debugfs entries nvmet-tcp: support secure channel concatenation nvmet: Add 'sq' argument to alloc_ctrl_args nvme-fabrics: reset admin connection for secure concatenation nvme-tcp: request secure channel concatenation nvme-keyring: add nvme_tls_psk_refresh() nvme: add nvme_auth_derive_tls_psk() nvme: add nvme_auth_generate_digest() ...
2025-03-25Merge tag 'crc-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux Pull CRC updates from Eric Biggers: "Another set of improvements to the kernel's CRC (cyclic redundancy check) code: - Rework the CRC64 library functions to be directly optimized, like what I did last cycle for the CRC32 and CRC-T10DIF library functions - Rewrite the x86 PCLMULQDQ-optimized CRC code, and add VPCLMULQDQ support and acceleration for crc64_be and crc64_nvme - Rewrite the riscv Zbc-optimized CRC code, and add acceleration for crc_t10dif, crc64_be, and crc64_nvme - Remove crc_t10dif and crc64_rocksoft from the crypto API, since they are no longer needed there - Rename crc64_rocksoft to crc64_nvme, as the old name was incorrect - Add kunit test cases for crc64_nvme and crc7 - Eliminate redundant functions for calculating the Castagnoli CRC32, settling on just crc32c() - Remove unnecessary prompts from some of the CRC kconfig options - Further optimize the x86 crc32c code" * tag 'crc-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux: (36 commits) x86/crc: drop the avx10_256 functions and rename avx10_512 to avx512 lib/crc: remove unnecessary prompt for CONFIG_CRC64 lib/crc: remove unnecessary prompt for CONFIG_LIBCRC32C lib/crc: remove unnecessary prompt for CONFIG_CRC8 lib/crc: remove unnecessary prompt for CONFIG_CRC7 lib/crc: remove unnecessary prompt for CONFIG_CRC4 lib/crc7: unexport crc7_be_syndrome_table lib/crc_kunit.c: update comment in crc_benchmark() lib/crc_kunit.c: add test and benchmark for crc7_be() x86/crc32: optimize tail handling for crc32c short inputs riscv/crc64: add Zbc optimized CRC64 functions riscv/crc-t10dif: add Zbc optimized CRC-T10DIF function riscv/crc32: reimplement the CRC32 functions using new template riscv/crc: add "template" for Zbc optimized CRC functions x86/crc: add ANNOTATE_NOENDBR to suppress objtool warnings x86/crc32: improve crc32c_arch() code generation with clang x86/crc64: implement crc64_be and crc64_nvme using new template x86/crc-t10dif: implement crc_t10dif using new template x86/crc32: implement crc32_le using new template x86/crc: add "template" for [V]PCLMULQDQ based CRC functions ...
2025-03-25Merge tag 'timers-cleanups-2025-03-23' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull timer cleanups from Thomas Gleixner: "A treewide hrtimer timer cleanup hrtimers are initialized with hrtimer_init() and a subsequent store to the callback pointer. This turned out to be suboptimal for the upcoming Rust integration and is obviously a silly implementation to begin with. This cleanup replaces the hrtimer_init(T); T->function = cb; sequence with hrtimer_setup(T, cb); The conversion was done with Coccinelle and a few manual fixups. Once the conversion has completely landed in mainline, hrtimer_init() will be removed and the hrtimer::function becomes a private member" * tag 'timers-cleanups-2025-03-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (100 commits) wifi: rt2x00: Switch to use hrtimer_update_function() io_uring: Use helper function hrtimer_update_function() serial: xilinx_uartps: Use helper function hrtimer_update_function() ASoC: fsl: imx-pcm-fiq: Switch to use hrtimer_setup() RDMA: Switch to use hrtimer_setup() virtio: mem: Switch to use hrtimer_setup() drm/vmwgfx: Switch to use hrtimer_setup() drm/xe/oa: Switch to use hrtimer_setup() drm/vkms: Switch to use hrtimer_setup() drm/msm: Switch to use hrtimer_setup() drm/i915/request: Switch to use hrtimer_setup() drm/i915/uncore: Switch to use hrtimer_setup() drm/i915/pmu: Switch to use hrtimer_setup() drm/i915/perf: Switch to use hrtimer_setup() drm/i915/gvt: Switch to use hrtimer_setup() drm/i915/huc: Switch to use hrtimer_setup() drm/amdgpu: Switch to use hrtimer_setup() stm class: heartbeat: Switch to use hrtimer_setup() i2c: Switch to use hrtimer_setup() iio: Switch to use hrtimer_setup() ...
2025-03-24Merge tag 'cgroup-for-6.15' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup Pull cgroup updates from Tejun Heo: - Add deprecation info messages to cgroup1-only features - rstat updates including a bug fix and breaking up a critical section to reduce interrupt latency impact - Other misc and doc updates * tag 'cgroup-for-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: rstat: Cleanup flushing functions and locking cgroup/rstat: avoid disabling irqs for O(num_cpu) mm: Fix a build breakage in memcontrol-v1.c blk-cgroup: Simplify policy files registration cgroup: Update file naming comment cgroup: Add deprecation message to legacy freezer controller mm: Add transformation message for per-memcg swappiness RFC cgroup/cpuset-v1: Add deprecation messages to sched_relax_domain_level cgroup/cpuset-v1: Add deprecation messages to memory_migrate cgroup/cpuset-v1: Add deprecation messages to mem_exclusive and mem_hardwall cgroup: Print message when /proc/cgroups is read on v2-only system cgroup/blkio: Add deprecation messages to reset_stats cgroup/cpuset-v1: Add deprecation messages to memory_spread_page and memory_spread_slab cgroup/cpuset-v1: Add deprecation messages to sched_load_balance and memory_pressure_enabled cgroup, docs: Be explicit about independence of RT_GROUP_SCHED and non-cpu controllers cgroup/rstat: Fix forceidle time in cpu.stat cgroup/misc: Remove unused misc_cg_res_total_usage cgroup/cpuset: Move procfs cpuset attribute under cgroup-v1.c cgroup: update comment about dropping cgroup kn refs
2025-03-24Merge tag 'vfs-6.15-rc1.pagesize' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs Pull vfs pagesize updates from Christian Brauner: "This enables block sizes greater than the page size for block devices. With this we can start supporting block devices with logical block sizes larger than 4k. It also allows to lift the device cache sector size support to 64k. This allows filesystems which can use larger sector sizes up to 64k to ensure that the filesystem will not generate writes that are smaller than the specified sector size" * tag 'vfs-6.15-rc1.pagesize' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: bdev: add back PAGE_SIZE block size validation for sb_set_blocksize() bdev: use bdev_io_min() for statx block size block/bdev: lift block size restrictions to 64k block/bdev: enable large folio support for large logical block sizes fs/buffer fs/mpage: remove large folio restriction fs/mpage: use blocks_per_folio instead of blocks_per_page fs/mpage: avoid negative shift for large blocksize fs/buffer: remove batching from async read fs/buffer: simplify block_read_full_folio() with bh_offset()
2025-03-19block/blk-iocost: ensure 'ret' is set on errorJens Axboe
In case blkg_conf_open_bdev_frozen() fails, ioc_qos_write() jumps to the error path without assigning a value to 'ret'. Ensure that it inherits the error from the passed back error value. Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202503200454.QWpwKeJu-lkp@intel.com/ Fixes: 9730763f4756 ("block: correct locking order for protecting blk-wbt parameters") Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-03-19block: correct locking order for protecting blk-wbt parametersNilay Shroff
The commit '245618f8e45f ("block: protect wbt_lat_usec using q-> elevator_lock")' introduced q->elevator_lock to protect updates to blk-wbt parameters when writing to the sysfs attribute wbt_ lat_usec and the cgroup attribute io.cost.qos. However, both these attributes also acquire q->rq_qos_mutex, leading to the following lockdep warning: ====================================================== WARNING: possible circular locking dependency detected 6.14.0-rc5+ #138 Not tainted ------------------------------------------------------ bash/5902 is trying to acquire lock: c000000085d495a0 (&q->rq_qos_mutex){+.+.}-{4:4}, at: wbt_init+0x164/0x238 but task is already holding lock: c000000085d498c8 (&q->elevator_lock){+.+.}-{4:4}, at: queue_wb_lat_store+0xb0/0x20c which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&q->elevator_lock){+.+.}-{4:4}: __mutex_lock+0xf0/0xa58 ioc_qos_write+0x16c/0x85c cgroup_file_write+0xc4/0x32c kernfs_fop_write_iter+0x1b8/0x29c vfs_write+0x410/0x584 ksys_write+0x84/0x140 system_call_exception+0x134/0x360 system_call_vectored_common+0x15c/0x2ec -> #0 (&q->rq_qos_mutex){+.+.}-{4:4}: __lock_acquire+0x1b6c/0x2ae0 lock_acquire+0x140/0x430 __mutex_lock+0xf0/0xa58 wbt_init+0x164/0x238 queue_wb_lat_store+0x1dc/0x20c queue_attr_store+0x12c/0x164 sysfs_kf_write+0x6c/0xb0 kernfs_fop_write_iter+0x1b8/0x29c vfs_write+0x410/0x584 ksys_write+0x84/0x140 system_call_exception+0x134/0x360 system_call_vectored_common+0x15c/0x2ec other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&q->elevator_lock); lock(&q->rq_qos_mutex); lock(&q->elevator_lock); lock(&q->rq_qos_mutex); *** DEADLOCK *** 6 locks held by bash/5902: #0: c000000051122400 (sb_writers#3){.+.+}-{0:0}, at: ksys_write+0x84/0x140 #1: c00000007383f088 (&of->mutex#2){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x174/0x29c #2: c000000008550428 (kn->active#182){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x180/0x29c #3: c000000085d493a8 (&q->q_usage_counter(io)#5){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x28/0x40 #4: c000000085d493e0 (&q->q_usage_counter(queue)#5){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x28/0x40 #5: c000000085d498c8 (&q->elevator_lock){+.+.}-{4:4}, at: queue_wb_lat_store+0xb0/0x20c stack backtrace: CPU: 17 UID: 0 PID: 5902 Comm: bash Kdump: loaded Not tainted 6.14.0-rc5+ #138 Hardware name: IBM,9043-MRX POWER10 (architected) 0x800200 0xf000006 of:IBM,FW1060.00 (NM1060_028) hv:phyp pSeries Call Trace: [c0000000721ef590] [c00000000118f8a8] dump_stack_lvl+0x108/0x18c (unreliable) [c0000000721ef5c0] [c00000000022563c] print_circular_bug+0x448/0x604 [c0000000721ef670] [c000000000225a44] check_noncircular+0x24c/0x26c [c0000000721ef740] [c00000000022bf28] __lock_acquire+0x1b6c/0x2ae0 [c0000000721ef870] [c000000000229240] lock_acquire+0x140/0x430 [c0000000721ef970] [c0000000011cfbec] __mutex_lock+0xf0/0xa58 [c0000000721efaa0] [c00000000096c46c] wbt_init+0x164/0x238 [c0000000721efaf0] [c0000000008f8cd8] queue_wb_lat_store+0x1dc/0x20c [c0000000721efb50] [c0000000008f8fa0] queue_attr_store+0x12c/0x164 [c0000000721efc60] [c0000000007c11cc] sysfs_kf_write+0x6c/0xb0 [c0000000721efca0] [c0000000007bfa4c] kernfs_fop_write_iter+0x1b8/0x29c [c0000000721efcf0] [c0000000006a281c] vfs_write+0x410/0x584 [c0000000721efdc0] [c0000000006a2cc8] ksys_write+0x84/0x140 [c0000000721efe10] [c000000000031b64] system_call_exception+0x134/0x360 [c0000000721efe50] [c00000000000cedc] system_call_vectored_common+0x15c/0x2ec >From the above log it's apparent that method which writes to sysfs attr wbt_lat_usec acquires q->elevator_lock first, and then acquires q->rq_ qos_mutex. However the another method which writes to io.cost.qos, acquires q->rq_qos_mutex first, and then acquires q->rq_qos_mutex. So this could potentially cause the deadlock. A closer look at ioc_qos_write shows that correcting the lock order is non-trivial because q->rq_qos_mutex is acquired in blkg_conf_open_bdev and released in blkg_conf_exit. The function blkg_conf_open_bdev is responsible for parsing user input and finding the corresponding block device (bdev) from the user provided major:minor number. Since we do not know the bdev until blkg_conf_open_bdev completes, we cannot simply move q->elevator_lock acquisition before blkg_conf_open_ bdev. So to address this, we intoduce new helpers blkg_conf_open_bdev_ frozen and blkg_conf_exit_frozen which are just wrappers around blkg_ conf_open_bdev and blkg_conf_exit respectively. The helper blkg_conf_ open_bdev_frozen is similar to blkg_conf_open_bdev, but additionally freezes the queue, acquires q->elevator_lock and ensures the correct locking order is followed between q->elevator_lock and q->rq_qos_mutex. Similarly another helper blkg_conf_exit_frozen in addition to unfreezing the queue ensures that we release the locks in correct order. By using these helpers, now we maintain the same locking order in all code paths where we update blk-wbt parameters. Fixes: 245618f8e45f ("block: protect wbt_lat_usec using q->elevator_lock") Reported-by: kernel test robot <oliver.sang@intel.com> Closes: https://lore.kernel.org/oe-lkp/202503171650.cc082b66-lkp@intel.com Signed-off-by: Nilay Shroff <nilay@linux.ibm.com> Link: https://lore.kernel.org/r/20250319105518.468941-3-nilay@linux.ibm.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-03-19block: release q->elevator_lock in ioc_qos_writeNilay Shroff
The ioc_qos_write method acquires q->elevator_lock to protect updates to blk-wbt parameters. Once these updates are complete, the lock should be released before returning from ioc_qos_write. However, in one code path, the release of q->elevator_lock was mistakenly omitted, potentially leading to a lock leak. This commit fixes the issue by ensuring that q->elevator_lock is properly released in all return paths of ioc_qos_write. Fixes: 245618f8e45f ("block: protect wbt_lat_usec using q->elevator_lock") Reported-by: kernel test robot <oliver.sang@intel.com> Closes: https://lore.kernel.org/oe-lkp/202503171650.cc082b66-lkp@intel.com Signed-off-by: Nilay Shroff <nilay@linux.ibm.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20250319105518.468941-2-nilay@linux.ibm.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-03-18blk-cgroup: improve policy registration error handlingChen Linxuan
This patch improve the returned error code of blkcg_policy_register(). 1. Move the validation check for cpd/pd_alloc_fn and cpd/pd_free_fn function pairs to the start of blkcg_policy_register(). This ensures we immediately return -EINVAL if the function pairs are not correctly provided, rather than returning -ENOSPC after locking and unlocking mutexes unnecessarily. Those locks should not contention any problems, as error of policy registration is a super cold path. 2. Return -ENOMEM when cpd_alloc_fn() failed. Co-authored-by: Wen Tao <wentao@uniontech.com> Signed-off-by: Wen Tao <wentao@uniontech.com> Signed-off-by: Chen Linxuan <chenlinxuan@uniontech.com> Reviewed-by: Michal Koutný <mkoutny@suse.com> Acked-by: Tejun Heo <tj@kernel.org> Reviewed-by: Yu Kuai <yukuai3@huawei.com> Link: https://lore.kernel.org/r/3E333A73B6B6DFC0+20250317022924.150907-1-chenlinxuan@uniontech.com Signed-off-by: Jens Axboe <axboe@kernel.dk>