Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756445Ab3G3RuJ (ORCPT ); Tue, 30 Jul 2013 13:50:09 -0400 Received: from e28smtp08.in.ibm.com ([122.248.162.8]:60617 "EHLO e28smtp08.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752800Ab3G3RuH (ORCPT ); Tue, 30 Jul 2013 13:50:07 -0400 From: "Aneesh Kumar K.V" To: Joonsoo Kim , Andrew Morton Cc: Rik van Riel , Mel Gorman , Michal Hocko , KAMEZAWA Hiroyuki , Hugh Dickins , Davidlohr Bueso , David Gibson , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Joonsoo Kim , Wanpeng Li , Naoya Horiguchi , Hillf Danton , Joonsoo Kim Subject: Re: [PATCH 06/18] mm, hugetlb: remove vma_need_reservation() In-Reply-To: <1375075929-6119-7-git-send-email-iamjoonsoo.kim@lge.com> References: <1375075929-6119-1-git-send-email-iamjoonsoo.kim@lge.com> <1375075929-6119-7-git-send-email-iamjoonsoo.kim@lge.com> User-Agent: Notmuch/0.15.2+167~g5306b2b (http://notmuchmail.org) Emacs/24.3.50.1 (x86_64-unknown-linux-gnu) Date: Tue, 30 Jul 2013 23:19:58 +0530 Message-ID: <87siywos3d.fsf@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13073017-2000-0000-0000-00000D1AD4AD Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8001 Lines: 229 Joonsoo Kim writes: > vma_need_reservation() can be substituted by vma_has_reserves() > with minor change. These function do almost same thing, > so unifying them is better to maintain. I found the resulting code confusing and complex. I am sure there is more that what is explained in the commit message. If you are just doing this for cleanup, may be we should avoid doing this ? > > Signed-off-by: Joonsoo Kim > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index bf2ee11..ff46a2c 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -451,8 +451,18 @@ void reset_vma_resv_huge_pages(struct vm_area_struct *vma) > vma->vm_private_data = (void *)0; > } > > -/* Returns true if the VMA has associated reserve pages */ > -static int vma_has_reserves(struct vm_area_struct *vma, long chg) > +/* > + * Determine if the huge page at addr within the vma has an associated > + * reservation. Where it does not we will need to logically increase > + * reservation and actually increase subpool usage before an allocation > + * can occur. Where any new reservation would be required the > + * reservation change is prepared, but not committed. Once the page > + * has been allocated from the subpool and instantiated the change should > + * be committed via vma_commit_reservation. No action is required on > + * failure. > + */ > +static int vma_has_reserves(struct hstate *h, > + struct vm_area_struct *vma, unsigned long addr) > { > if (vma->vm_flags & VM_NORESERVE) { > /* > @@ -464,10 +474,22 @@ static int vma_has_reserves(struct vm_area_struct *vma, long chg) > * step. Currently, we don't have any other solution to deal > * with this situation properly, so add work-around here. > */ > - if (vma->vm_flags & VM_MAYSHARE && chg == 0) > - return 1; > - else > - return 0; > + if (vma->vm_flags & VM_MAYSHARE) { > + struct address_space *mapping = vma->vm_file->f_mapping; > + struct inode *inode = mapping->host; > + pgoff_t idx = vma_hugecache_offset(h, vma, addr); > + struct resv_map *resv = inode->i_mapping->private_data; > + long chg; > + > + chg = region_chg(resv, idx, idx + 1); > + if (chg < 0) > + return -ENOMEM; > + > + if (chg == 0) > + return 1; > + } > + > + return 0; > } > > /* Shared mappings always use reserves */ > @@ -478,8 +500,16 @@ static int vma_has_reserves(struct vm_area_struct *vma, long chg) > * Only the process that called mmap() has reserves for > * private mappings. > */ > - if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) > + if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) { > + pgoff_t idx = vma_hugecache_offset(h, vma, addr); > + struct resv_map *resv = vma_resv_map(vma); > + > + /* Just for allocating region structure */ > + if (region_chg(resv, idx, idx + 1) < 0) > + return -ENOMEM; > + > return 1; > + } > > return 0; > } > @@ -542,8 +572,7 @@ static struct page *dequeue_huge_page_node(struct hstate *h, int nid) > > static struct page *dequeue_huge_page_vma(struct hstate *h, > struct vm_area_struct *vma, > - unsigned long address, int avoid_reserve, > - long chg) > + unsigned long address, int avoid_reserve) > { > struct page *page = NULL; > struct mempolicy *mpol; > @@ -558,7 +587,7 @@ static struct page *dequeue_huge_page_vma(struct hstate *h, > * have no page reserves. This check ensures that reservations are > * not "stolen". The child may still get SIGKILLed > */ > - if (!vma_has_reserves(vma, chg) && > + if (!vma_has_reserves(h, vma, address) && > h->free_huge_pages - h->resv_huge_pages == 0) > return NULL; > > @@ -578,7 +607,7 @@ retry_cpuset: > if (page) { > if (avoid_reserve) > break; > - if (!vma_has_reserves(vma, chg)) > + if (!vma_has_reserves(h, vma, address)) > break; > > h->resv_huge_pages--; > @@ -1077,42 +1106,6 @@ static void return_unused_surplus_pages(struct hstate *h, > } > } > > -/* > - * Determine if the huge page at addr within the vma has an associated > - * reservation. Where it does not we will need to logically increase > - * reservation and actually increase subpool usage before an allocation > - * can occur. Where any new reservation would be required the > - * reservation change is prepared, but not committed. Once the page > - * has been allocated from the subpool and instantiated the change should > - * be committed via vma_commit_reservation. No action is required on > - * failure. > - */ > -static long vma_needs_reservation(struct hstate *h, > - struct vm_area_struct *vma, unsigned long addr) > -{ > - struct address_space *mapping = vma->vm_file->f_mapping; > - struct inode *inode = mapping->host; > - > - if (vma->vm_flags & VM_MAYSHARE) { > - pgoff_t idx = vma_hugecache_offset(h, vma, addr); > - struct resv_map *resv = inode->i_mapping->private_data; > - > - return region_chg(resv, idx, idx + 1); > - > - } else if (!is_vma_resv_set(vma, HPAGE_RESV_OWNER)) { > - return 1; > - > - } else { > - long err; > - pgoff_t idx = vma_hugecache_offset(h, vma, addr); > - struct resv_map *resv = vma_resv_map(vma); > - > - err = region_chg(resv, idx, idx + 1); > - if (err < 0) > - return err; > - return 0; > - } > -} > static void vma_commit_reservation(struct hstate *h, > struct vm_area_struct *vma, unsigned long addr) > { > @@ -1140,8 +1133,7 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma, > struct hugepage_subpool *spool = subpool_vma(vma); > struct hstate *h = hstate_vma(vma); > struct page *page; > - long chg; > - int ret, idx; > + int ret, idx, has_reserve; > struct hugetlb_cgroup *h_cg; > > idx = hstate_index(h); > @@ -1153,20 +1145,21 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma, > * need pages and subpool limit allocated allocated if no reserve > * mapping overlaps. > */ > - chg = vma_needs_reservation(h, vma, addr); > - if (chg < 0) > + has_reserve = vma_has_reserves(h, vma, addr); > + if (has_reserve < 0) > return ERR_PTR(-ENOMEM); > - if (chg) > - if (hugepage_subpool_get_pages(spool, chg)) > + > + if (!has_reserve && (hugepage_subpool_get_pages(spool, 1) < 0)) > return ERR_PTR(-ENOSPC); > > ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg); > if (ret) { > - hugepage_subpool_put_pages(spool, chg); > + if (!has_reserve) > + hugepage_subpool_put_pages(spool, 1); > return ERR_PTR(-ENOSPC); > } > spin_lock(&hugetlb_lock); > - page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve, chg); > + page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve); > if (!page) { > spin_unlock(&hugetlb_lock); > page = alloc_buddy_huge_page(h, NUMA_NO_NODE); > @@ -1174,7 +1167,8 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma, > hugetlb_cgroup_uncharge_cgroup(idx, > pages_per_huge_page(h), > h_cg); > - hugepage_subpool_put_pages(spool, chg); > + if (!has_reserve) > + hugepage_subpool_put_pages(spool, 1); > return ERR_PTR(-ENOSPC); > } > spin_lock(&hugetlb_lock); > @@ -2769,7 +2763,7 @@ retry: > * the spinlock. > */ > if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) > - if (vma_needs_reservation(h, vma, address) < 0) { > + if (vma_has_reserves(h, vma, address) < 0) { > ret = VM_FAULT_OOM; > goto backout_unlocked; > } > @@ -2860,7 +2854,7 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, > * consumed. > */ > if ((flags & FAULT_FLAG_WRITE) && !huge_pte_write(entry)) { > - if (vma_needs_reservation(h, vma, address) < 0) { > + if (vma_has_reserves(h, vma, address) < 0) { > ret = VM_FAULT_OOM; > goto out_mutex; > } > -- > 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/