From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f69.google.com (mail-wm0-f69.google.com [74.125.82.69]) by kanga.kvack.org (Postfix) with ESMTP id EF398280273 for ; Mon, 26 Sep 2016 05:01:24 -0400 (EDT) Received: by mail-wm0-f69.google.com with SMTP id b130so76755000wmc.2 for ; Mon, 26 Sep 2016 02:01:24 -0700 (PDT) Received: from mail-wm0-f68.google.com (mail-wm0-f68.google.com. [74.125.82.68]) by mx.google.com with ESMTPS id uw3si13272879wjb.68.2016.09.26.02.01.23 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 26 Sep 2016 02:01:23 -0700 (PDT) Received: by mail-wm0-f68.google.com with SMTP id b184so13030949wma.3 for ; Mon, 26 Sep 2016 02:01:23 -0700 (PDT) Date: Mon, 26 Sep 2016 11:01:22 +0200 From: Michal Hocko Subject: Re: [PATCH] mm: remove unnecessary condition in remove_inode_hugepages Message-ID: <20160926090121.GC28550@dhcp22.suse.cz> References: <1474857253-35702-1-git-send-email-zhongjiang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1474857253-35702-1-git-send-email-zhongjiang@huawei.com> Sender: owner-linux-mm@kvack.org List-ID: To: zhongjiang Cc: mike.kravetz@oracle.com, akpm@linux-foundation.org, n-horiguchi@ah.jp.nec.com, linux-mm@kvack.org On Mon 26-09-16 10:34:13, zhongjiang wrote: > From: zhong jiang > > 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 > --- > 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. > 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 -- Michal Hocko SUSE Labs -- 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: email@kvack.org