On Wed, Sep 04, 2024 at 10:29:31AM -0700, SeongJae Park wrote: > damon_test_three_regions_in_vmas() initializes a maple tree with > MM_MT_FLAGS. The flags contains MT_FLAGS_LOCK_EXTERN, which means > mt_lock of the maple tree will not be used. And therefore the maple > tree initialization code skips initialization of the mt_lock. However, > __link_vmas(), which adds vmas for test to the maple tree, uses the > mt_lock. In other words, the uninitialized spinlock is used. The > problem becomes clear when spinlock debugging is turned on, since it > reports spinlock bad magic bug. > > Fix the issue by excluding MT_FLAGS_LOCK_EXTERN from the maple tree > initialization flags. Note that we don't use empty flags to make it > further similar to the usage of mm maple tree, and to be prepared for > possible future changes, as suggested by Liam. > > Reported-by: Guenter Roeck <linux@xxxxxxxxxxxx> > Closes: https://lore.kernel.org/1453b2b2-6119-4082-ad9e-f3c5239bf87e@xxxxxxxxxxxx > Fixes: d0cf3dd47f0d ("damon: convert __damon_va_three_regions to use the VMA iterator") > Suggested-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx> > Signed-off-by: SeongJae Park <sj@xxxxxxxxxx> Tested-by: Guenter Roeck <linux@xxxxxxxxxxxx> > --- > Changes from v1 > (https://lore.kernel.org/20240904004534.1189-1-sj@xxxxxxxxxx) > - Keep lock usage and update the initialization flags (Liam) > - Fix a typo: s/celar/clear/ (Guenter) > > mm/damon/tests/vaddr-kunit.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/damon/tests/vaddr-kunit.h b/mm/damon/tests/vaddr-kunit.h > index 83626483f82b..a339d117150f 100644 > --- a/mm/damon/tests/vaddr-kunit.h > +++ b/mm/damon/tests/vaddr-kunit.h > @@ -77,7 +77,7 @@ static void damon_test_three_regions_in_vmas(struct kunit *test) > (struct vm_area_struct) {.vm_start = 307, .vm_end = 330}, > }; > > - mt_init_flags(&mm.mm_mt, MM_MT_FLAGS); > + mt_init_flags(&mm.mm_mt, MT_FLAGS_ALLOC_RANGE | MT_FLAGS_USE_RCU); > if (__link_vmas(&mm.mm_mt, vmas, ARRAY_SIZE(vmas))) > kunit_skip(test, "Failed to create VMA tree"); > > -- > 2.39.2 >
