This is a note to let you know that I've just added the patch titled
staging: lustre: disable preempt while sampling processor id.
to the 4.15-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:
staging-lustre-disable-preempt-while-sampling-processor-id.patch
and it can be found in the queue-4.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Mon Apr 9 10:16:32 CEST 2018
From: NeilBrown <neilb@xxxxxxxx>
Date: Tue, 19 Dec 2017 10:01:47 +1100
Subject: staging: lustre: disable preempt while sampling processor id.
From: NeilBrown <neilb@xxxxxxxx>
[ Upstream commit dbeccabf5294e80f7cc9ee566746c42211bed736 ]
Calling smp_processor_id() without disabling preemption
triggers a warning (if CONFIG_DEBUG_PREEMPT).
I think the result of cfs_cpt_current() is only used as a hint for
load balancing, rather than as a precise and stable indicator of
the current CPU. So it doesn't need to be called with
preemption disabled.
So disable preemption inside cfs_cpt_current() to silence the warning.
Signed-off-by: NeilBrown <neilb@xxxxxxxx>
Reviewed-by: Andreas Dilger <andreas.dilger@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/staging/lustre/lnet/libcfs/linux/linux-cpu.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
--- a/drivers/staging/lustre/lnet/libcfs/linux/linux-cpu.c
+++ b/drivers/staging/lustre/lnet/libcfs/linux/linux-cpu.c
@@ -529,19 +529,20 @@ EXPORT_SYMBOL(cfs_cpt_spread_node);
int
cfs_cpt_current(struct cfs_cpt_table *cptab, int remap)
{
- int cpu = smp_processor_id();
- int cpt = cptab->ctb_cpu2cpt[cpu];
+ int cpu;
+ int cpt;
- if (cpt < 0) {
- if (!remap)
- return cpt;
+ preempt_disable();
+ cpu = smp_processor_id();
+ cpt = cptab->ctb_cpu2cpt[cpu];
+ if (cpt < 0 && remap) {
/* don't return negative value for safety of upper layer,
* instead we shadow the unknown cpu to a valid partition ID
*/
cpt = cpu % cptab->ctb_nparts;
}
-
+ preempt_enable();
return cpt;
}
EXPORT_SYMBOL(cfs_cpt_current);
Patches currently in stable-queue which might be from neilb@xxxxxxxx are
queue-4.15/staging-lustre-disable-preempt-while-sampling-processor-id.patch
queue-4.15/vfs-close-race-between-getcwd-and-d_move.patch