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authorNeilBrown <neilb@suse.com>2015-08-03 09:09:57 +0200
committerNeilBrown <neilb@suse.com>2015-08-03 09:10:56 +0200
commit49895bcc7e566ba455eb2996607d6fbd3447ce16 (patch)
treee62f0eb74f454df5f6e219eba25ca965a591abd2 /drivers/md
parentmd: use kzalloc() when bitmap is disabled (diff)
downloadlinux-49895bcc7e566ba455eb2996607d6fbd3447ce16.tar.xz
linux-49895bcc7e566ba455eb2996607d6fbd3447ce16.zip
md/raid5: don't let shrink_slab shrink too far.
I have a report of drop_one_stripe() called from raid5_cache_scan() apparently finding ->max_nr_stripes == 0. This should not be allowed. So add a test to keep max_nr_stripes above min_nr_stripes. Also use a 'mask' rather than a 'mod' in drop_one_stripe to ensure 'hash' is valid even if max_nr_stripes does reach zero. Fixes: edbe83ab4c27 ("md/raid5: allow the stripe_cache to grow and shrink.") Cc: stable@vger.kernel.org (4.1 - please release with 2d5b569b665) Reported-by: Tomas Papan <tomas.papan@gmail.com> Signed-off-by: NeilBrown <neilb@suse.com>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/raid5.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 643d217bfa13..f757023fc458 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2256,7 +2256,7 @@ static int resize_stripes(struct r5conf *conf, int newsize)
static int drop_one_stripe(struct r5conf *conf)
{
struct stripe_head *sh;
- int hash = (conf->max_nr_stripes - 1) % NR_STRIPE_HASH_LOCKS;
+ int hash = (conf->max_nr_stripes - 1) & STRIPE_HASH_LOCKS_MASK;
spin_lock_irq(conf->hash_locks + hash);
sh = get_free_stripe(conf, hash);
@@ -6388,7 +6388,8 @@ static unsigned long raid5_cache_scan(struct shrinker *shrink,
if (mutex_trylock(&conf->cache_size_mutex)) {
ret= 0;
- while (ret < sc->nr_to_scan) {
+ while (ret < sc->nr_to_scan &&
+ conf->max_nr_stripes > conf->min_nr_stripes) {
if (drop_one_stripe(conf) == 0) {
ret = SHRINK_STOP;
break;