[Devel] [PATCH RHEL7 COMMIT] kasan: remove the unnecessary WARN_ONCE from quarantine.c

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-693.1.1.vz7.37.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-693.1.1.vz7.37.4
------>
commit 9dfe388cc0130624b7a089f4160ae2239abdd2cd
Author: Alexander Potapenko <glider at google.com>
Date:   Fri Sep 15 17:27:29 2017 +0300

    kasan: remove the unnecessary WARN_ONCE from quarantine.c
    
    It's quite unlikely that the user will so little memory that the per-CPU
    quarantines won't fit into the given fraction of the available memory.
    Even in that case he won't be able to do anything with the information
    given in the warning.
    
    Link: http://lkml.kernel.org/r/1470929182-101413-1-git-send-email-glider@google.com
    Signed-off-by: Alexander Potapenko <glider at google.com>
    Acked-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
    Cc: Dmitry Vyukov <dvyukov at google.com>
    Cc: Andrey Konovalov <adech.fo at gmail.com>
    Cc: Christoph Lameter <cl at linux.com>
    Cc: Joonsoo Kim <iamjoonsoo.kim at lge.com>
    Cc: Kuthonuzo Luruo <kuthonuzo.luruo at hpe.com>
    Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
    
    https://jira.sw.ru/browse/PSBM-69081
    (cherry picked from commit bcbf0d566b6e59a6e873bfe415cc415111a819e2)
    Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
---
 mm/kasan/quarantine.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c
index b6728a3..baabaad 100644
--- a/mm/kasan/quarantine.c
+++ b/mm/kasan/quarantine.c
@@ -217,11 +217,8 @@ void quarantine_reduce(void)
 	new_quarantine_size = (READ_ONCE(totalram_pages) << PAGE_SHIFT) /
 		QUARANTINE_FRACTION;
 	percpu_quarantines = QUARANTINE_PERCPU_SIZE * num_online_cpus();
-	if (WARN_ONCE(new_quarantine_size < percpu_quarantines,
-		"Too little memory, disabling global KASAN quarantine.\n"))
-		new_quarantine_size = 0;
-	else
-		new_quarantine_size -= percpu_quarantines;
+	new_quarantine_size = (new_quarantine_size < percpu_quarantines) ?
+		0 : new_quarantine_size - percpu_quarantines;
 	WRITE_ONCE(quarantine_size, new_quarantine_size);
 
 	last = global_quarantine.head;