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blk-iocost: Pass gendisk to ioc_refresh_params

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Current kernel (d2980d8d82) crashes
when blk_iocost_init for `nvme1` disk.

	BUG: kernel NULL pointer dereference, address: 0000000000000050
	#PF: supervisor read access in kernel mode
	#PF: error_code(0x0000) - not-present page

	blk_iocost_init (include/asm-generic/qspinlock.h:128
			 include/linux/spinlock.h:203
			 include/linux/spinlock_api_smp.h:158
			 include/linux/spinlock.h:400
			 block/blk-iocost.c:2884)
	ioc_qos_write (block/blk-iocost.c:3198)
	? kretprobe_perf_func (kernel/trace/trace_kprobe.c:1566)
	? kernfs_fop_write_iter (include/linux/slab.h:584 fs/kernfs/file.c:311)
	? __kmem_cache_alloc_node (mm/slab.h:? mm/slub.c:3452 mm/slub.c:3491)
	? _copy_from_iter (arch/x86/include/asm/uaccess_64.h:46
			   arch/x86/include/asm/uaccess_64.h:52
			   lib/iov_iter.c:183 lib/iov_iter.c:628)
	? kretprobe_dispatcher (kernel/trace/trace_kprobe.c:1693)
	cgroup_file_write (kernel/cgroup/cgroup.c:4061)
	kernfs_fop_write_iter (fs/kernfs/file.c:334)
	vfs_write (include/linux/fs.h:1849 fs/read_write.c:491
		   fs/read_write.c:584)
	ksys_write (fs/read_write.c:637)
	do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80)
	entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120)

This happens because ioc_refresh_params() is being called without
a properly initialized ioc->rqos, which is happening later in the callee
side.

ioc_refresh_params() -> ioc_autop_idx() tries to access
ioc->rqos.disk->queue but ioc->rqos.disk is NULL, causing the BUG above.

Create function, called ioc_refresh_params_disk(), that is similar to
ioc_refresh_params() but where the "struct gendisk" could be passed as
an explicit argument. This function will be called when ioc->rqos.disk
is not initialized.

Fixes: ce57b55860 ("blk-rq-qos: make rq_qos_add and rq_qos_del more useful")

Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230228111654.1778120-1-leitao@debian.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Breno Leitao 2023-02-28 03:16:54 -08:00 committed by Jens Axboe
parent 310726c33a
commit e33b93650f
1 changed files with 20 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
block/blk-iocost.c
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@ -800,7 +800,11 @@ static void ioc_refresh_period_us(struct ioc *ioc)
ioc_refresh_margins(ioc);
}
static int ioc_autop_idx(struct ioc *ioc)
/*
* ioc->rqos.disk isn't initialized when this function is called from
* the init path.
*/
static int ioc_autop_idx(struct ioc *ioc, struct gendisk *disk)
{
int idx = ioc->autop_idx;
const struct ioc_params *p = &autop[idx];
@ -808,11 +812,11 @@ static int ioc_autop_idx(struct ioc *ioc)
u64 now_ns;
/* rotational? */
if (!blk_queue_nonrot(ioc->rqos.disk->queue))
if (!blk_queue_nonrot(disk->queue))
return AUTOP_HDD;
/* handle SATA SSDs w/ broken NCQ */
if (blk_queue_depth(ioc->rqos.disk->queue) == 1)
if (blk_queue_depth(disk->queue) == 1)
return AUTOP_SSD_QD1;
/* use one of the normal ssd sets */
@ -901,14 +905,19 @@ static void ioc_refresh_lcoefs(struct ioc *ioc)
&c[LCOEF_WPAGE], &c[LCOEF_WSEQIO], &c[LCOEF_WRANDIO]);
}
static bool ioc_refresh_params(struct ioc *ioc, bool force)
/*
* struct gendisk is required as an argument because ioc->rqos.disk
* is not properly initialized when called from the init path.
*/
static bool ioc_refresh_params_disk(struct ioc *ioc, bool force,
struct gendisk *disk)
{
const struct ioc_params *p;
int idx;
lockdep_assert_held(&ioc->lock);
idx = ioc_autop_idx(ioc);
idx = ioc_autop_idx(ioc, disk);
p = &autop[idx];
if (idx == ioc->autop_idx && !force)
@ -939,6 +948,11 @@ static bool ioc_refresh_params(struct ioc *ioc, bool force)
return true;
}
static bool ioc_refresh_params(struct ioc *ioc, bool force)
{
return ioc_refresh_params_disk(ioc, force, ioc->rqos.disk);
}
/*
* When an iocg accumulates too much vtime or gets deactivated, we throw away
* some vtime, which lowers the overall device utilization. As the exact amount
@ -2880,7 +2894,7 @@ static int blk_iocost_init(struct gendisk *disk)
spin_lock_irq(&ioc->lock);
ioc->autop_idx = AUTOP_INVALID;
ioc_refresh_params(ioc, true);
ioc_refresh_params_disk(ioc, true, disk);
spin_unlock_irq(&ioc->lock);
/*