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 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: staging-lustre-disable-preempt-while-sampling-processor-id.patch and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From foo@baz Mon Apr 9 13:58:16 CEST 2018
From: NeilBrown neilb@suse.com Date: Tue, 19 Dec 2017 10:01:47 +1100 Subject: staging: lustre: disable preempt while sampling processor id.
From: NeilBrown neilb@suse.com
[ 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@suse.com Reviewed-by: Andreas Dilger andreas.dilger@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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 @@ -528,19 +528,20 @@ 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@suse.com are
queue-4.14/staging-lustre-disable-preempt-while-sampling-processor-id.patch queue-4.14/vfs-close-race-between-getcwd-and-d_move.patch