The patch titled Subject: kasan: don't call find_vm_area() in RT kernel has been added to the -mm mm-hotfixes-unstable branch. Its filename is kasan-dont-call-find_vm_area-in-rt-kernel.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: Waiman Long longman@redhat.com Subject: kasan: don't call find_vm_area() in RT kernel Date: Tue, 11 Feb 2025 11:07:50 -0500

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

print_address_description() is run with a raw_spinlock_t acquired and interrupt disabled. find_vm_area() 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.

Link: https://lkml.kernel.org/r/20250211160750.1301353-1-longman@redhat.com Fixes: c056a364e954 ("kasan: print virtual mapping info in reports") Signed-off-by: Waiman Long longman@redhat.com Cc: Alexander Potapenko glider@google.com Cc: Andrey Konovalov andreyknvl@gmail.com Cc: Andrey Ryabinin ryabinin.a.a@gmail.com Cc: Dmitriy Vyukov dvyukov@google.com Cc: Steven Rostedt rostedt@goodmis.org Cc: Mariano Pache npache@redhat.com Cc: Sebastian Andrzej Siewior bigeasy@linutronix.de Cc: Vincenzo Frascino vincenzo.frascino@arm.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/kasan/report.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-)

--- a/mm/kasan/report.c~kasan-dont-call-find_vm_area-in-rt-kernel +++ a/mm/kasan/report.c @@ -398,9 +398,20 @@ static void print_address_description(vo 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(vo

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"); _

Patches currently in -mm which might be from longman@redhat.com are

kasan-dont-call-find_vm_area-in-rt-kernel.patch