diff options
| author | Hugh Dickins <hughd@google.com> | 2013-02-22 16:34:33 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-02-23 17:50:17 -0800 |
| commit | 340ef3902cf20cec43cdcd1e72ae5cb518be7328 (patch) | |
| tree | 98051b821bc3749510dc7e27f14051902aa54743 /mm/huge_memory.c | |
| parent | 75980e97daccfc6babbac7e180ff118537955f5d (diff) | |
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.c | 28 |
1 files changed, 9 insertions, 19 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 9db521fa8e8..f40b2ce23d6 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; } |