The patch titled Subject: kasan: make report_lock a raw spinlock has been added to the -mm mm-hotfixes-unstable branch. Its filename is kasan-make-report_lock-a-raw-spinlock.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

Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days

------------------------------------------------------ From: Jared Kangas jkangas@redhat.com Subject: kasan: make report_lock a raw spinlock Date: Tue, 19 Nov 2024 13:02:34 -0800

If PREEMPT_RT is enabled, report_lock is a sleeping spinlock and must not be locked when IRQs are disabled. However, KASAN reports may be triggered in such contexts. For example:

char *s = kzalloc(1, GFP_KERNEL); kfree(s); local_irq_disable(); char c = *s; /* KASAN report here leads to spin_lock() */ local_irq_enable();

Make report_spinlock a raw spinlock to prevent rescheduling when PREEMPT_RT is enabled.

Link: https://lkml.kernel.org/r/20241119210234.1602529-1-jkangas@redhat.com Signed-off-by: Jared Kangas jkangas@redhat.com Cc: Alexander Potapenko glider@google.com Cc: Andrey Konovalov andreyknvl@gmail.com Cc: Andrey Ryabinin ryabinin.a.a@gmail.com Cc: Dmitry Vyukov dvyukov@google.com 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 | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/mm/kasan/report.c~kasan-make-report_lock-a-raw-spinlock +++ a/mm/kasan/report.c @@ -200,7 +200,7 @@ static inline void fail_non_kasan_kunit_

#endif /* CONFIG_KUNIT */

-static DEFINE_SPINLOCK(report_lock); +static DEFINE_RAW_SPINLOCK(report_lock);

static void start_report(unsigned long *flags, bool sync) { @@ -211,7 +211,7 @@ static void start_report(unsigned long * lockdep_off(); /* Make sure we don't end up in loop. */ report_suppress_start(); - spin_lock_irqsave(&report_lock, *flags); + raw_spin_lock_irqsave(&report_lock, *flags); pr_err("==================================================================\n"); }

@@ -221,7 +221,7 @@ static void end_report(unsigned long *fl trace_error_report_end(ERROR_DETECTOR_KASAN, (unsigned long)addr); pr_err("==================================================================\n"); - spin_unlock_irqrestore(&report_lock, *flags); + raw_spin_unlock_irqrestore(&report_lock, *flags); if (!test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) check_panic_on_warn("KASAN"); switch (kasan_arg_fault) { _

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

kasan-make-report_lock-a-raw-spinlock.patch