diff options
| author | Tomas Glozar <tglozar@redhat.com> | 2023-09-20 07:37:12 +0200 |
|---|---|---|
| committer | Ira Weiny <ira.weiny@intel.com> | 2023-09-27 10:33:47 -0700 |
| commit | 36c75ce3bd299878fd9b238e9803d3817ddafbf3 (patch) | |
| tree | 6ddf4052d708980dab8366dac355de24a50e3442 /drivers/nvdimm | |
| parent | 6fd4ebfc4d61e3097b595ab2725d513e3bbd6739 (diff) | |
| download | linux-36c75ce3bd299878fd9b238e9803d3817ddafbf3.tar.gz | |
nd_btt: Make BTT lanes preemptible
nd_region_acquire_lane uses get_cpu, which disables preemption. This is
an issue on PREEMPT_RT kernels, since btt_write_pg and also
nd_region_acquire_lane itself take a spin lock, resulting in BUG:
sleeping function called from invalid context.
Fix the issue by replacing get_cpu with smp_process_id and
migrate_disable when needed. This makes BTT operations preemptible, thus
permitting the use of spin_lock.
BUG example occurring when running ndctl tests on PREEMPT_RT kernel:
BUG: sleeping function called from invalid context at
kernel/locking/spinlock_rt.c:48
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 4903, name:
libndctl
preempt_count: 1, expected: 0
RCU nest depth: 0, expected: 0
Preemption disabled at:
[<ffffffffc1313db5>] nd_region_acquire_lane+0x15/0x90 [libnvdimm]
Call Trace:
<TASK>
dump_stack_lvl+0x8e/0xb0
__might_resched+0x19b/0x250
rt_spin_lock+0x4c/0x100
? btt_write_pg+0x2d7/0x500 [nd_btt]
btt_write_pg+0x2d7/0x500 [nd_btt]
? local_clock_noinstr+0x9/0xc0
btt_submit_bio+0x16d/0x270 [nd_btt]
__submit_bio+0x48/0x80
__submit_bio_noacct+0x7e/0x1e0
submit_bio_wait+0x58/0xb0
__blkdev_direct_IO_simple+0x107/0x240
? inode_set_ctime_current+0x51/0x110
? __pfx_submit_bio_wait_endio+0x10/0x10
blkdev_write_iter+0x1d8/0x290
vfs_write+0x237/0x330
...
</TASK>
Fixes: 5212e11fde4d ("nd_btt: atomic sector updates")
Signed-off-by: Tomas Glozar <tglozar@redhat.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Diffstat (limited to 'drivers/nvdimm')
| -rw-r--r-- | drivers/nvdimm/region_devs.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c index 0a81f87f6f6c0..e2f1fb99707fc 100644 --- a/drivers/nvdimm/region_devs.c +++ b/drivers/nvdimm/region_devs.c @@ -939,7 +939,8 @@ unsigned int nd_region_acquire_lane(struct nd_region *nd_region) { unsigned int cpu, lane; - cpu = get_cpu(); + migrate_disable(); + cpu = smp_processor_id(); if (nd_region->num_lanes < nr_cpu_ids) { struct nd_percpu_lane *ndl_lock, *ndl_count; @@ -958,16 +959,15 @@ EXPORT_SYMBOL(nd_region_acquire_lane); void nd_region_release_lane(struct nd_region *nd_region, unsigned int lane) { if (nd_region->num_lanes < nr_cpu_ids) { - unsigned int cpu = get_cpu(); + unsigned int cpu = smp_processor_id(); struct nd_percpu_lane *ndl_lock, *ndl_count; ndl_count = per_cpu_ptr(nd_region->lane, cpu); ndl_lock = per_cpu_ptr(nd_region->lane, lane); if (--ndl_count->count == 0) spin_unlock(&ndl_lock->lock); - put_cpu(); } - put_cpu(); + migrate_enable(); } EXPORT_SYMBOL(nd_region_release_lane); |