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authorHugh Dickins <hughd@google.com>2013-02-23 01:34:33 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2013-02-24 02:50:17 +0100
commit340ef3902cf20cec43cdcd1e72ae5cb518be7328 (patch)
tree98051b821bc3749510dc7e27f14051902aa54743 /mm/huge_memory.c
parentmm: fold page->_last_nid into page->flags where possible (diff)
downloadlinux-340ef3902cf20cec43cdcd1e72ae5cb518be7328.tar.xz
linux-340ef3902cf20cec43cdcd1e72ae5cb518be7328.zip
mm: numa: cleanup flow of transhuge page migration
When correcting commit 04fa5d6a6547 ("mm: migrate: check page_count of THP before migrating") Hugh Dickins noted that the control flow for transhuge migration was difficult to follow. Unconditionally calling put_page() in numamigrate_isolate_page() made the failure paths of both migrate_misplaced_transhuge_page() and migrate_misplaced_page() more complex that they should be. Further, he was extremely wary that an unlock_page() should ever happen after a put_page() even if the put_page() should never be the final put_page. Hugh implemented the following cleanup to simplify the path by calling putback_lru_page() inside numamigrate_isolate_page() if it failed to isolate and always calling unlock_page() within migrate_misplaced_transhuge_page(). There is no functional change after this patch is applied but the code is easier to follow and unlock_page() always happens before put_page(). [mgorman@suse.de: changelog only] Signed-off-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Simon Jeons <simon.jeons@gmail.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/huge_memory.c')
-rw-r--r--mm/huge_memory.c28
1 files changed, 9 insertions, 19 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 9db521fa8e8a..f40b2ce23d60 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1296,7 +1296,6 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
int target_nid;
int current_nid = -1;
bool migrated;
- bool page_locked = false;
spin_lock(&mm->page_table_lock);
if (unlikely(!pmd_same(pmd, *pmdp)))
@@ -1318,7 +1317,6 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
/* Acquire the page lock to serialise THP migrations */
spin_unlock(&mm->page_table_lock);
lock_page(page);
- page_locked = true;
/* Confirm the PTE did not while locked */
spin_lock(&mm->page_table_lock);
@@ -1331,34 +1329,26 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
/* Migrate the THP to the requested node */
migrated = migrate_misplaced_transhuge_page(mm, vma,
- pmdp, pmd, addr,
- page, target_nid);
- if (migrated)
- current_nid = target_nid;
- else {
- spin_lock(&mm->page_table_lock);
- if (unlikely(!pmd_same(pmd, *pmdp))) {
- unlock_page(page);
- goto out_unlock;
- }
- goto clear_pmdnuma;
- }
+ pmdp, pmd, addr, page, target_nid);
+ if (!migrated)
+ goto check_same;
- task_numa_fault(current_nid, HPAGE_PMD_NR, migrated);
+ task_numa_fault(target_nid, HPAGE_PMD_NR, true);
return 0;
+check_same:
+ spin_lock(&mm->page_table_lock);
+ if (unlikely(!pmd_same(pmd, *pmdp)))
+ goto out_unlock;
clear_pmdnuma:
pmd = pmd_mknonnuma(pmd);
set_pmd_at(mm, haddr, pmdp, pmd);
VM_BUG_ON(pmd_numa(*pmdp));
update_mmu_cache_pmd(vma, addr, pmdp);
- if (page_locked)
- unlock_page(page);
-
out_unlock:
spin_unlock(&mm->page_table_lock);
if (current_nid != -1)
- task_numa_fault(current_nid, HPAGE_PMD_NR, migrated);
+ task_numa_fault(current_nid, HPAGE_PMD_NR, false);
return 0;
}