| Message ID | 20221102110611.1085175-4-glider@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [1/5] kmsan: core: kmsan_in_runtime() should return true in NMI context | expand |
On Wed, Nov 02, 2022 at 12:06:10PM +0100, Alexander Potapenko wrote: > As pointed out by Peter Zijlstra, __msan_poison_alloca() does not play > well with IRQ code when PREEMPT_RT is on, because in that mode even > GFP_ATOMIC allocations cannot be performed. > > Fixing this would require making stackdepot completely lockless, which > is quite challenging and may be excessive for the time being. > > Instead, make sure KMSAN is incompatible with PREEMPT_RT, like other > debug configs are. > > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Dmitry Vyukov <dvyukov@google.com> > Cc: Marco Elver <elver@google.com> > Cc: Peter Zijlstra (Intel) <peterz@infradead.org> > Link: https://lore.kernel.org/lkml/20221025221755.3810809-1-glider@google.com/ > Signed-off-by: Alexander Potapenko <glider@google.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> > --- > lib/Kconfig.kmsan | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/lib/Kconfig.kmsan b/lib/Kconfig.kmsan > index b2489dd6503fa..ef2c8f256c57d 100644 > --- a/lib/Kconfig.kmsan > +++ b/lib/Kconfig.kmsan > @@ -12,6 +12,7 @@ config KMSAN > bool "KMSAN: detector of uninitialized values use" > depends on HAVE_ARCH_KMSAN && HAVE_KMSAN_COMPILER > depends on SLUB && DEBUG_KERNEL && !KASAN && !KCSAN > + depends on !PREEMPT_RT > select STACKDEPOT > select STACKDEPOT_ALWAYS_INIT > help > -- > 2.38.1.273.g43a17bfeac-goog >
diff --git a/lib/Kconfig.kmsan b/lib/Kconfig.kmsan index b2489dd6503fa..ef2c8f256c57d 100644 --- a/lib/Kconfig.kmsan +++ b/lib/Kconfig.kmsan @@ -12,6 +12,7 @@ config KMSAN bool "KMSAN: detector of uninitialized values use" depends on HAVE_ARCH_KMSAN && HAVE_KMSAN_COMPILER depends on SLUB && DEBUG_KERNEL && !KASAN && !KCSAN + depends on !PREEMPT_RT select STACKDEPOT select STACKDEPOT_ALWAYS_INIT help
As pointed out by Peter Zijlstra, __msan_poison_alloca() does not play well with IRQ code when PREEMPT_RT is on, because in that mode even GFP_ATOMIC allocations cannot be performed. Fixing this would require making stackdepot completely lockless, which is quite challenging and may be excessive for the time being. Instead, make sure KMSAN is incompatible with PREEMPT_RT, like other debug configs are. Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Marco Elver <elver@google.com> Cc: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/lkml/20221025221755.3810809-1-glider@google.com/ Signed-off-by: Alexander Potapenko <glider@google.com> --- lib/Kconfig.kmsan | 1 + 1 file changed, 1 insertion(+)