This is a note to let you know that I've just added the patch titled
s390: disable preemption when switching to nodat stack with CALL_ON_STACK
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
s390-disable-preemption-when-switching-to-nodat-stac.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 84f298c980aba6fc02bd1cb96d03b868713fb871
Author: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Date: Fri Nov 22 12:19:16 2019 +0100
s390: disable preemption when switching to nodat stack with CALL_ON_STACK
[ Upstream commit 7f28dad395243c5026d649136823bbc40029a828 ]
Make sure preemption is disabled when temporary switching to nodat
stack with CALL_ON_STACK helper, because nodat stack is per cpu.
Reviewed-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Signed-off-by: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/s390/kernel/machine_kexec.c b/arch/s390/kernel/machine_kexec.c
index d402ced7f7c3..cb8b1cc285c9 100644
--- a/arch/s390/kernel/machine_kexec.c
+++ b/arch/s390/kernel/machine_kexec.c
@@ -164,7 +164,9 @@ static bool kdump_csum_valid(struct kimage *image)
#ifdef CONFIG_CRASH_DUMP
int rc;
+ preempt_disable();
rc = CALL_ON_STACK(do_start_kdump, S390_lowcore.nodat_stack, 1, image);
+ preempt_enable();
return rc == 0;
#else
return false;
diff --git a/arch/s390/mm/maccess.c b/arch/s390/mm/maccess.c
index 59ad7997fed1..de7ca4b6718f 100644
--- a/arch/s390/mm/maccess.c
+++ b/arch/s390/mm/maccess.c
@@ -119,9 +119,15 @@ static unsigned long __no_sanitize_address _memcpy_real(unsigned long dest,
*/
int memcpy_real(void *dest, void *src, size_t count)
{
- if (S390_lowcore.nodat_stack != 0)
- return CALL_ON_STACK(_memcpy_real, S390_lowcore.nodat_stack,
- 3, dest, src, count);
+ int rc;
+
+ if (S390_lowcore.nodat_stack != 0) {
+ preempt_disable();
+ rc = CALL_ON_STACK(_memcpy_real, S390_lowcore.nodat_stack, 3,
+ dest, src, count);
+ preempt_enable();
+ return rc;
+ }
/*
* This is a really early memcpy_real call, the stacks are
* not set up yet. Just call _memcpy_real on the early boot
