kernel/linux.git/include/linux/genhd.h, branch linux-4.20.y

block: use rcu_work instead of call_rcu to avoid sleep in softirq

2019-01-22T20:09:57+00:00

commit 94a2c3a32b62e868dc1e3d854326745a7f1b8c7a upstream. We recently got a stack by syzkaller like this: BUG: sleeping function called from invalid context at mm/slab.h:361 in_atomic(): 1, irqs_disabled(): 0, pid: 6644, name: blkid INFO: lockdep is turned off. CPU: 1 PID: 6644 Comm: blkid Not tainted 4.4.163-514.55.6.9.x86_64+ #76 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 0000000000000000 5ba6a6b879e50c00 ffff8801f6b07b10 ffffffff81cb2194 0000000041b58ab3 ffffffff833c7745 ffffffff81cb2080 5ba6a6b879e50c00 0000000000000000 0000000000000001 0000000000000004 0000000000000000 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0x114/0x1a0 lib/dump_stack.c:51 [] ___might_sleep+0x291/0x490 kernel/sched/core.c:7675 [] __might_sleep+0xb3/0x270 kernel/sched/core.c:7637 [] slab_pre_alloc_hook mm/slab.h:361 [inline] [] slab_alloc_node mm/slub.c:2610 [inline] [] slab_alloc mm/slub.c:2692 [inline] [] kmem_cache_alloc_trace+0x2c3/0x5c0 mm/slub.c:2709 [] kmalloc include/linux/slab.h:479 [inline] [] kzalloc include/linux/slab.h:623 [inline] [] kobject_uevent_env+0x2c7/0x1150 lib/kobject_uevent.c:227 [] kobject_uevent+0x1f/0x30 lib/kobject_uevent.c:374 [] kobject_cleanup lib/kobject.c:633 [inline] [] kobject_release+0x229/0x440 lib/kobject.c:675 [] kref_sub include/linux/kref.h:73 [inline] [] kref_put include/linux/kref.h:98 [inline] [] kobject_put+0x72/0xd0 lib/kobject.c:692 [] put_device+0x25/0x30 drivers/base/core.c:1237 [] delete_partition_rcu_cb+0x1d4/0x2f0 block/partition-generic.c:232 [] __rcu_reclaim kernel/rcu/rcu.h:118 [inline] [] rcu_do_batch kernel/rcu/tree.c:2705 [inline] [] invoke_rcu_callbacks kernel/rcu/tree.c:2973 [inline] [] __rcu_process_callbacks kernel/rcu/tree.c:2940 [inline] [] rcu_process_callbacks+0x59c/0x1c70 kernel/rcu/tree.c:2957 [] __do_softirq+0x299/0xe20 kernel/softirq.c:273 [] invoke_softirq kernel/softirq.c:350 [inline] [] irq_exit+0x216/0x2c0 kernel/softirq.c:391 [] exiting_irq arch/x86/include/asm/apic.h:652 [inline] [] smp_apic_timer_interrupt+0x8b/0xc0 arch/x86/kernel/apic/apic.c:926 [] apic_timer_interrupt+0xa5/0xb0 arch/x86/entry/entry_64.S:746 [] ? audit_kill_trees+0x180/0x180 [] fd_install+0x57/0x80 fs/file.c:626 [] do_sys_open+0x45e/0x550 fs/open.c:1043 [] SYSC_open fs/open.c:1055 [inline] [] SyS_open+0x32/0x40 fs/open.c:1050 [] entry_SYSCALL_64_fastpath+0x1e/0x9a In softirq context, we call rcu callback function delete_partition_rcu_cb(), which may allocate memory by kzalloc with GFP_KERNEL flag. If the allocation cannot be satisfied, it may sleep. However, That is not allowed in softirq contex. Although we found this problem on linux 4.4, the latest kernel version seems to have this problem as well. And it is very similar to the previous one: https://lkml.org/lkml/2018/7/9/391 Fix it by using RCU workqueue, which allows sleep. Reviewed-by: Paul E. McKenney Signed-off-by: Yufen Yu Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

Merge tag 'v4.19-rc6' into for-4.20/block

2018-10-01T14:58:57+00:00

Merge -rc6 in, for two reasons: 1) Resolve a trivial conflict in the blk-mq-tag.c documentation 2) A few important regression fixes went into upstream directly, so they aren't in the 4.20 branch. Signed-off-by: Jens Axboe * tag 'v4.19-rc6': (780 commits) Linux 4.19-rc6 MAINTAINERS: fix reference to moved drivers/{misc => auxdisplay}/panel.c cpufreq: qcom-kryo: Fix section annotations perf/core: Add sanity check to deal with pinned event failure xen/blkfront: correct purging of persistent grants Revert "xen/blkfront: When purging persistent grants, keep them in the buffer" selftests/powerpc: Fix Makefiles for headers_install change blk-mq: I/O and timer unplugs are inverted in blktrace dax: Fix deadlock in dax_lock_mapping_entry() x86/boot: Fix kexec booting failure in the SEV bit detection code bcache: add separate workqueue for journal_write to avoid deadlock drm/amd/display: Fix Edid emulation for linux drm/amd/display: Fix Vega10 lightup on S3 resume drm/amdgpu: Fix vce work queue was not cancelled when suspend Revert "drm/panel: Add device_link from panel device to DRM device" xen/blkfront: When purging persistent grants, keep them in the buffer clocksource/drivers/timer-atmel-pit: Properly handle error cases block: fix deadline elevator drain for zoned block devices ACPI / hotplug / PCI: Don't scan for non-hotplug bridges if slot is not bridge drm/syncobj: Don't leak fences when WAIT_FOR_SUBMIT is set ... Signed-off-by: Jens Axboe

block: genhd: add 'groups' argument to device_add_disk

2018-09-28T14:30:28+00:00

Update device_add_disk() to take an 'groups' argument so that individual drivers can register a device with additional sysfs attributes. This avoids race condition the driver would otherwise have if these groups were to be created with sysfs_add_groups(). Signed-off-by: Martin Wilck Signed-off-by: Hannes Reinecke Reviewed-by: Christoph Hellwig Reviewed-by: Bart Van Assche Signed-off-by: Jens Axboe

block: use nanosecond resolution for iostat

2018-09-22T02:26:59+00:00

Klaus Kusche reported that the I/O busy time in /proc/diskstats was not updating properly on 4.18. This is because we started using ktime to track elapsed time, and we convert nanoseconds to jiffies when we update the partition counter. However, this gets rounded down, so any I/Os that take less than a jiffy are not accounted for. Previously in this case, the value of jiffies would sometimes increment while we were doing I/O, so at least some I/Os were accounted for. Let's convert the stats to use nanoseconds internally. We still report milliseconds as before, now more accurately than ever. The value is still truncated to 32 bits for backwards compatibility. Fixes: 522a777566f5 ("block: consolidate struct request timestamp fields") Cc: stable@vger.kernel.org Reported-by: Klaus Kusche Signed-off-by: Omar Sandoval Signed-off-by: Jens Axboe

block: Track DISCARD statistics and output them in stat and diskstat

2018-07-18T14:44:22+00:00

Add tracking of REQ_OP_DISCARD ios to the partition statistics and append them to the various stat files in /sys as well as /proc/diskstats. These are tracked with the same four stats as reads and writes: Number of discard ios completed. Number of discard ios merged Number of discard sectors completed Milliseconds spent on discard requests This is done via adding a new STAT_DISCARD define to genhd.h and then using it to index that stat field for discard requests. tj: Refreshed on top of v4.17 and other previous updates. Signed-off-by: Michael Callahan Signed-off-by: Tejun Heo Cc: Andy Newell Signed-off-by: Jens Axboe

block: Define and use STAT_READ and STAT_WRITE

2018-07-18T14:44:18+00:00

Add defines for STAT_READ and STAT_WRITE for indexing the partition stat entries. This clarifies some fs/ code which has hardcoded 1 for STAT_WRITE and will make it easier to extend the stats with additional fields. tj: Refreshed on top of v4.17. Signed-off-by: Michael Callahan Signed-off-by: Tejun Heo Cc: "Theodore Ts'o" Cc: Jaegeuk Kim Signed-off-by: Jens Axboe

block: Add part_stat_read_accum to read across field entries.

2018-07-18T14:44:16+00:00

Add a part_stat_read_accum macro to genhd.h to read and sum across field entries. For example to sum up the number read and write sectors completed. In addition to being ar reasonable cleanup by itself this will make it easier to add new stat fields in the future. tj: Refreshed on top of v4.17. Signed-off-by: Michael Callahan Signed-off-by: Tejun Heo Signed-off-by: Jens Axboe

blk-mq: fix sysfs inflight counter

2018-04-26T15:02:01+00:00

When the blk-mq inflight implementation was added, /proc/diskstats was converted to use it, but /sys/block/$dev/inflight was not. Fix it by adding another helper to count in-flight requests by data direction. Fixes: f299b7c7a9de ("blk-mq: provide internal in-flight variant") Signed-off-by: Omar Sandoval Signed-off-by: Jens Axboe

genhd: Fix BUG in blkdev_open()

2018-02-26T16:48:42+00:00

When two blkdev_open() calls for a partition race with device removal and recreation, we can hit BUG_ON(!bd_may_claim(bdev, whole, holder)) in blkdev_open(). The race can happen as follows: CPU0 CPU1 CPU2 del_gendisk() bdev_unhash_inode(part1); blkdev_open(part1, O_EXCL) blkdev_open(part1, O_EXCL) bdev = bd_acquire() bdev = bd_acquire() blkdev_get(bdev) bd_start_claiming(bdev) - finds old inode 'whole' bd_prepare_to_claim() -> 0 bdev_unhash_inode(whole); blkdev_get(bdev); bd_start_claiming(bdev) - finds new inode 'whole' bd_prepare_to_claim() - this also succeeds as we have different 'whole' here... - bad things happen now as we have two exclusive openers of the same bdev The problem here is that block device opens can see various intermediate states while gendisk is shutting down and then being recreated. We fix the problem by introducing new lookup_sem in gendisk that synchronizes gendisk deletion with get_gendisk() and furthermore by making sure that get_gendisk() does not return gendisk that is being (or has been) deleted. This makes sure that once we ever manage to look up newly created bdev inode, we are also guaranteed that following get_gendisk() will either return failure (and we fail open) or it returns gendisk for the new device and following bdget_disk() will return new bdev inode (i.e., blkdev_open() follows the path as if it is completely run after new device is created). Reported-and-analyzed-by: Hou Tao Tested-by: Hou Tao Signed-off-by: Jan Kara Signed-off-by: Jens Axboe

genhd: Add helper put_disk_and_module()

2018-02-26T16:48:42+00:00

Add a proper counterpart to get_disk_and_module() - put_disk_and_module(). Currently it is opencoded in several places. Signed-off-by: Jan Kara Signed-off-by: Jens Axboe