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    SubjectRe: [RFC] remove unnecessary condition in remove_inode_hugepages
    [CC Naoya]

    On Fri 23-09-16 09:53:52, zhong jiang wrote:
    >
    > At present, we need to call hugetlb_fix_reserve_count when hugetlb_unrserve_pages fails,
    > and PagePrivate will decide hugetlb reserves counts.
    >
    > we obtain the page from page cache. and use page both lock_page and mutex_lock.
    > alloc_huge_page add page to page chace always hold lock page, then bail out clearpageprivate
    > before unlock page.
    >
    > but I' m not sure it is right or I miss the points.
    >
    >
    > diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
    > index 4ea71eb..010723b 100644
    > --- a/fs/hugetlbfs/inode.c
    > +++ b/fs/hugetlbfs/inode.c
    > @@ -462,14 +462,12 @@ static void remove_inode_hugepages(struct inode *inode, loff_t lstart,
    > * the page, note PagePrivate which is used in case
    > * of error.
    > */
    > - rsv_on_error = !PagePrivate(page);
    > 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);
    >
    >
    > --
    > To unsubscribe, send a message with 'unsubscribe linux-mm' in
    > the body to majordomo@kvack.org. For more info on Linux MM,
    > see: http://www.linux-mm.org/ .
    > Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

    --
    Michal Hocko
    SUSE Labs

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