The patch titled
Subject: kmsan: make sure PREEMPT_RT is off
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
kmsan-make-sure-preempt_rt-is-off.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/kmsan-make-sure-preempt_rt-is-off.patch
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: Alexander Potapenko <glider@xxxxxxxxxx>
Subject: kmsan: make sure PREEMPT_RT is off
Date: Wed, 2 Nov 2022 12:06:10 +0100
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.
Link: https://lkml.kernel.org/r/20221102110611.1085175-4-glider@xxxxxxxxxx
Link: https://lore.kernel.org/lkml/20221025221755.3810809-1-glider@xxxxxxxxxx/
Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Masahiro Yamada <masahiroy@xxxxxxxxxx>
Cc: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/Kconfig.kmsan | 1 +
1 file changed, 1 insertion(+)
--- a/lib/Kconfig.kmsan~kmsan-make-sure-preempt_rt-is-off
+++ a/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
_
Patches currently in -mm which might be from glider@xxxxxxxxxx are
kmsan-core-kmsan_in_runtime-should-return-true-in-nmi-context.patch
x86-uaccess-instrument-copy_from_user_nmi.patch
kconfigdebug-ensure-early-check-for-kmsan-in-config_kmsan_warn.patch
kmsan-make-sure-preempt_rt-is-off.patch
x86-traps-avoid-kmsan-bugs-originating-from-handle_bug.patch
