Re: [PATCH] mm: remove unnecessary condition in remove_inode_hugepages
From: Michal Hocko <mhocko@kernel.org>
Date: 2016-09-26 09:01:24
On Mon 26-09-16 10:34:13, zhongjiang wrote:
quoted hunk ↗ jump to hunk
From: zhong jiang <redacted> when the huge page is added to the page cahce (huge_add_to_page_cache), the page private flag will be cleared. since this code (remove_inode_hugepages) will only be called for pages in the page cahce, PagePrivate(page) will always be false. The patch remove the code without any functional change. Signed-off-by: zhong jiang <redacted> --- fs/hugetlbfs/inode.c | 10 ++++------ include/linux/hugetlb.h | 2 +- mm/hugetlb.c | 4 ++-- 3 files changed, 7 insertions(+), 9 deletions(-)diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index 4ea71eb..81f8bbf4 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c@@ -458,18 +458,16 @@ static void remove_inode_hugepages(struct inode *inode, loff_t lstart, * cache (remove_huge_page) BEFORE removing the * region/reserve map (hugetlb_unreserve_pages). In * rare out of memory conditions, removal of the - * region/reserve map could fail. Before free'ing - * the page, note PagePrivate which is used in case - * of error. + * region/reserve map could fail. Correspondingly, + * the subpool and global reserve usage count can need + * to be adjusted. */ - rsv_on_error = !PagePrivate(page);
This whole code is tricky as hell. I would be calmer if we just stick a VM_BUG_ON here to make sure that this assumption will not break later on.
quoted hunk ↗ jump to hunk
remove_huge_page(page); freed++; if (!truncate_op) { if (unlikely(hugetlb_unreserve_pages(inode, next, next + 1, 1))) - hugetlb_fix_reserve_counts(inode, - rsv_on_error); + hugetlb_fix_reserve_counts(inode); } unlock_page(page);diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index c26d463..d2e0fc5 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h@@ -90,7 +90,7 @@ int dequeue_hwpoisoned_huge_page(struct page *page); bool isolate_huge_page(struct page *page, struct list_head *list); void putback_active_hugepage(struct page *page); void free_huge_page(struct page *page); -void hugetlb_fix_reserve_counts(struct inode *inode, bool restore_reserve); +void hugetlb_fix_reserve_counts(struct inode *inode); extern struct mutex *hugetlb_fault_mutex_table; u32 hugetlb_fault_mutex_hash(struct hstate *h, struct mm_struct *mm, struct vm_area_struct *vma,diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 87e11d8..28a079a 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c@@ -567,13 +567,13 @@ retry: * appear as a "reserved" entry instead of simply dangling with incorrect * counts. */ -void hugetlb_fix_reserve_counts(struct inode *inode, bool restore_reserve) +void hugetlb_fix_reserve_counts(struct inode *inode) { struct hugepage_subpool *spool = subpool_inode(inode); long rsv_adjust; rsv_adjust = hugepage_subpool_get_pages(spool, 1); - if (restore_reserve && rsv_adjust) { + if (rsv_adjust) { struct hstate *h = hstate_inode(inode); hugetlb_acct_memory(h, 1);-- 1.8.3.1
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