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.
Signed-off-by: Waiman Long <longman@xxxxxxxxxx>
---
mm/kasan/report.c | 20 ++++++++++++++++++--
1 file changed, 18 insertions(+), 2 deletions(-)
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 3fe77a360f1c..e1ee687966aa 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -398,9 +398,20 @@ static void print_address_description(void *addr, u8 tag,
pr_err("\n");
}
- if (is_vmalloc_addr(addr)) {
- struct vm_struct *va = find_vm_area(addr);
+ if (!is_vmalloc_addr(addr))
+ goto print_page;
+ /*
+ * RT kernel cannot call find_vm_area() in atomic context.
+ * For !RT kernel, prevent spinlock_t inside raw_spinlock_t warning
+ * by raising wait-type to WAIT_SLEEP.
+ */
+ if (!IS_ENABLED(CONFIG_PREEMPT_RT)) {
+ static DEFINE_WAIT_OVERRIDE_MAP(vmalloc_map, LD_WAIT_SLEEP);
+ struct vm_struct *va;
+
+ lock_map_acquire_try(&vmalloc_map);
+ va = find_vm_area(addr);
if (va) {
pr_err("The buggy address belongs to the virtual mapping at\n"
" [%px, %px) created by:\n"
@@ -410,8 +421,13 @@ static void print_address_description(void *addr, u8 tag,
page = vmalloc_to_page(addr);
}
+ lock_map_release(&vmalloc_map);
+ } else {
+ pr_err("The buggy address %px belongs to a vmalloc virtual mapping\n",
+ addr);
}
+print_page:
if (page) {
pr_err("The buggy address belongs to the physical page:\n");
dump_page(page, "kasan: bad access detected");
--
2.48.1
