From: Miaohe Lin <linmiaohe@xxxxxxxxxx> Subject: mm/hugetlb: avoid calculating fault_mutex_hash in truncate_op case The fault_mutex hashing overhead can be avoided in truncate_op case because page faults can not race with truncation in this routine. So calculate hash for fault_mutex only in !truncate_op case to save some cpu cycles. Link: https://lkml.kernel.org/r/20210308112809.26107-6-linmiaohe@xxxxxxxxxx Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/hugetlbfs/inode.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/fs/hugetlbfs/inode.c~mm-hugetlb-avoid-calculating-fault_mutex_hash-in-truncate_op-case +++ a/fs/hugetlbfs/inode.c @@ -482,10 +482,9 @@ static void remove_inode_hugepages(struc for (i = 0; i < pagevec_count(&pvec); ++i) { struct page *page = pvec.pages[i]; - u32 hash; + u32 hash = 0; index = page->index; - hash = hugetlb_fault_mutex_hash(mapping, index); if (!truncate_op) { /* * Only need to hold the fault mutex in the @@ -493,6 +492,7 @@ static void remove_inode_hugepages(struc * page faults. Races are not possible in the * case of truncation. */ + hash = hugetlb_fault_mutex_hash(mapping, index); mutex_lock(&hugetlb_fault_mutex_table[hash]); } _
