From 4c3ffd058c28bb1aac30a68d1f02de4a2077823e Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Fri, 6 Jan 2017 14:19:58 +1100 Subject: [PATCH] SUNRPC: two small improvements to rpcauth shrinker. 1/ If we find an entry that is too young to be pruned, return SHRINK_STOP to ensure we don't get called again. This is more correct, and avoids wasting a little CPU time. Prior to 3.12, it can prevent drop_slab() from spinning indefinitely. 2/ Return a precise number from rpcauth_cache_shrink_count(), rather than rounding down to a multiple of 100 (of whatever sysctl_vfs_cache_pressure is). This ensures that when we "echo 3 > /proc/sys/vm/drop_caches", this cache is still purged, even if it has fewer than 100 entires. Neither of these are really important, they just make behaviour more predicatable, which can be helpful when debugging related issues. Signed-off-by: NeilBrown Signed-off-by: Anna Schumaker --- net/sunrpc/auth.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c index 2bff63a73cf8..d8f17ea7932e 100644 --- a/net/sunrpc/auth.c +++ b/net/sunrpc/auth.c @@ -464,8 +464,10 @@ rpcauth_prune_expired(struct list_head *free, int nr_to_scan) * Note that the cred_unused list must be time-ordered. */ if (time_in_range(cred->cr_expire, expired, jiffies) && - test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) + test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) { + freed = SHRINK_STOP; break; + } list_del_init(&cred->cr_lru); number_cred_unused--; @@ -520,7 +522,7 @@ static unsigned long rpcauth_cache_shrink_count(struct shrinker *shrink, struct shrink_control *sc) { - return (number_cred_unused / 100) * sysctl_vfs_cache_pressure; + return number_cred_unused * sysctl_vfs_cache_pressure / 100; } static void -- 2.20.1