On 2/11/25 5:57 PM, Andrew Morton wrote:
On Tue, 11 Feb 2025 11:07:50 -0500 Waiman Long <longman@xxxxxxxxxx> wrote:The following bug report appeared with a test run in a RT debug kernel. [ 3359.353842] BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 [ 3359.353848] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 140605, name: kunit_try_catch [ 3359.353853] preempt_count: 1, expected: 0 : [ 3359.353933] Call trace: : [ 3359.353955] rt_spin_lock+0x70/0x140 [ 3359.353959] find_vmap_area+0x84/0x168 [ 3359.353963] find_vm_area+0x1c/0x50 [ 3359.353966] print_address_description.constprop.0+0x2a0/0x320 [ 3359.353972] print_report+0x108/0x1f8 [ 3359.353976] kasan_report+0x90/0xc8 [ 3359.353980] __asan_load1+0x60/0x70 The print_address_description() is run with a raw_spinlock_t acquired and interrupt disabled. The find_vm_area() function needs to acquire a spinlock_t which becomes a sleeping lock in the RT kernel. IOW, we can't call find_vm_area() in a RT kernel. Fix this bug report by skipping the find_vm_area() call in this case and just print out the address as is. For !RT kernel, follow the example set in commit 0cce06ba859a ("debugobjects,locking: Annotate debug_object_fill_pool() wait type violation") and use DEFINE_WAIT_OVERRIDE_MAP() to avoid a spinlock_t inside raw_spinlock_t warning.Thanks. I added it and shall await review from the KASAN developers. I'm thinking we add Fixes: c056a364e954 ("kasan: print virtual mapping info in reports") Cc: <stable@xxxxxxxxxxxxxxx> but c056a364e954 is 3 years old and I don't think we care about -rt in such old kernels. Thoughts?
The KASAN report_lock was changed to a raw_spinlock_t in v6.13 kernel with commit e30a0361b851 ("kasan: make report_lock a raw spinlock") to fix a similar RT problem. The report_lock is acquired before calling print_address_description(). Before commit e30a0361b851, this find_vm_area() is a secondary issue. We may consider commit e30a0361b851 isn't complete and this is a fix for that.
The DEFINE_WAIT_OVERRIDE_MAP() macro was introduced in v6.4. So this patch cannot be backported to a version earlier than that unless commit 0cce06ba859a is there.
Cheers, Longman
