Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.1 086/159] md/raid5: dont let shrink_slab shrink too far. | Date | Sat, 26 Sep 2015 13:55:32 -0700 |
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4.1-stable review patch. If anyone has any objections, please let me know.
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From: NeilBrown <neilb@suse.com>
commit 49895bcc7e566ba455eb2996607d6fbd3447ce16 upstream.
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.") Reported-by: Tomas Papan <tomas.papan@gmail.com> Signed-off-by: NeilBrown <neilb@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/md/raid5.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
--- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -2245,7 +2245,7 @@ static int resize_stripes(struct r5conf 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); @@ -6375,7 +6375,8 @@ static unsigned long raid5_cache_scan(st 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;
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