Originally mm_walk->skip is used to determine whether we walk over a vma or not. But this is not enough because one of the page table walker's caller subpage_mark_vma_nohuge(), will need another behavior PTWALK_BREAK, which let us break current loop and continue from the beginning of the next loop.
To implement this behavior and make it extensible for future users, this patch replaces mm_walk->skip with more flexible mm_walk->control, and changes its default value to PTWALK_NEXT (which is equivalent to present walk->skip == 1.) This is because PTWALK_NEXT provides the behavior which is most likely to be used globally. Signed-off-by: Naoya Horiguchi <[email protected]> --- fs/proc/task_mmu.c | 20 +++++++------- include/linux/mm.h | 13 ++++++--- mm/memcontrol.c | 5 ++-- mm/mempolicy.c | 3 +-- mm/pagewalk.c | 79 +++++++++++++++++++++++++++++++++--------------------- 5 files changed, 71 insertions(+), 49 deletions(-) diff --git v3.15-rc8-mmots-2014-06-03-16-28.orig/fs/proc/task_mmu.c v3.15-rc8-mmots-2014-06-03-16-28/fs/proc/task_mmu.c index fa6d6a4e85b3..2864028ae2f8 100644 --- v3.15-rc8-mmots-2014-06-03-16-28.orig/fs/proc/task_mmu.c +++ v3.15-rc8-mmots-2014-06-03-16-28/fs/proc/task_mmu.c @@ -502,9 +502,8 @@ static int smaps_pmd(pmd_t *pmd, unsigned long addr, unsigned long end, smaps_pte((pte_t *)pmd, addr, addr + HPAGE_PMD_SIZE, walk); spin_unlock(ptl); mss->anonymous_thp += HPAGE_PMD_SIZE; - /* don't call smaps_pte() */ - walk->skip = 1; - } + } else + walk->control = PTWALK_DOWN; return 0; } @@ -762,13 +761,14 @@ static int clear_refs_test_walk(unsigned long start, unsigned long end, * Writing 4 to /proc/pid/clear_refs affects all pages. */ if (cp->type == CLEAR_REFS_ANON && vma->vm_file) - walk->skip = 1; + return 0; if (cp->type == CLEAR_REFS_MAPPED && !vma->vm_file) - walk->skip = 1; + return 0; if (cp->type == CLEAR_REFS_SOFT_DIRTY) { if (vma->vm_flags & VM_SOFTDIRTY) vma->vm_flags &= ~VM_SOFTDIRTY; } + walk->control = PTWALK_DOWN; return 0; } @@ -1006,9 +1006,8 @@ static int pagemap_pmd(pmd_t *pmd, unsigned long addr, unsigned long end, break; } spin_unlock(ptl); - /* don't call pagemap_pte() */ - walk->skip = 1; - } + } else + walk->control = PTWALK_DOWN; return err; } @@ -1288,9 +1287,8 @@ static int gather_pmd_stats(pmd_t *pmd, unsigned long addr, gather_stats(page, md, pte_dirty(huge_pte), HPAGE_PMD_SIZE/PAGE_SIZE); spin_unlock(ptl); - /* don't call gather_pte_stats() */ - walk->skip = 1; - } + } else + walk->control = PTWALK_DOWN; return 0; } #ifdef CONFIG_HUGETLB_PAGE diff --git v3.15-rc8-mmots-2014-06-03-16-28.orig/include/linux/mm.h v3.15-rc8-mmots-2014-06-03-16-28/include/linux/mm.h index b4aa6579f2b1..43449eba3032 100644 --- v3.15-rc8-mmots-2014-06-03-16-28.orig/include/linux/mm.h +++ v3.15-rc8-mmots-2014-06-03-16-28/include/linux/mm.h @@ -1106,8 +1106,7 @@ void unmap_vmas(struct mmu_gather *tlb, struct vm_area_struct *start_vma, * right now." 0 means "skip the current vma." * @mm: mm_struct representing the target process of page table walk * @vma: vma currently walked - * @skip: internal control flag which is set when we skip the lower - * level entries. + * @control: walk control flag * @private: private data for callbacks' use * * (see the comment on walk_page_range() for more details) @@ -1125,10 +1124,18 @@ struct mm_walk { struct mm_walk *walk); struct mm_struct *mm; struct vm_area_struct *vma; - int skip; + int control; void *private; }; +enum mm_walk_control { + PTWALK_NEXT = 0, /* Go to the next entry in the same level or + * the next vma. This is default behavior. */ + PTWALK_DOWN, /* Go down to lower level */ + PTWALK_BREAK, /* Break current loop and continue from the + * next loop */ +}; + int walk_page_range(unsigned long addr, unsigned long end, struct mm_walk *walk); int walk_page_vma(struct vm_area_struct *vma, struct mm_walk *walk); diff --git v3.15-rc8-mmots-2014-06-03-16-28.orig/mm/memcontrol.c v3.15-rc8-mmots-2014-06-03-16-28/mm/memcontrol.c index 6970857ba0c8..aeab82bce739 100644 --- v3.15-rc8-mmots-2014-06-03-16-28.orig/mm/memcontrol.c +++ v3.15-rc8-mmots-2014-06-03-16-28/mm/memcontrol.c @@ -6729,9 +6729,8 @@ static int mem_cgroup_count_precharge_pmd(pmd_t *pmd, if (get_mctgt_type_thp(vma, addr, *pmd, NULL) == MC_TARGET_PAGE) mc.precharge += HPAGE_PMD_NR; spin_unlock(ptl); - /* don't call mem_cgroup_count_precharge_pte() */ - walk->skip = 1; - } + } else + skip->control = PTWALK_DOWN; return 0; } diff --git v3.15-rc8-mmots-2014-06-03-16-28.orig/mm/mempolicy.c v3.15-rc8-mmots-2014-06-03-16-28/mm/mempolicy.c index cf3b995b21d0..cc9dc8c06bcb 100644 --- v3.15-rc8-mmots-2014-06-03-16-28.orig/mm/mempolicy.c +++ v3.15-rc8-mmots-2014-06-03-16-28/mm/mempolicy.c @@ -596,7 +596,6 @@ static int queue_pages_test_walk(unsigned long start, unsigned long end, } qp->prev = vma; - walk->skip = 1; if (vma->vm_flags & VM_PFNMAP) return 0; @@ -610,7 +609,7 @@ static int queue_pages_test_walk(unsigned long start, unsigned long end, ((flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) && vma_migratable(vma))) /* queue pages from current vma */ - walk->skip = 0; + walk->control = PTWALK_DOWN; return 0; } diff --git v3.15-rc8-mmots-2014-06-03-16-28.orig/mm/pagewalk.c v3.15-rc8-mmots-2014-06-03-16-28/mm/pagewalk.c index 15c7585e8684..385efd59178f 100644 --- v3.15-rc8-mmots-2014-06-03-16-28.orig/mm/pagewalk.c +++ v3.15-rc8-mmots-2014-06-03-16-28/mm/pagewalk.c @@ -3,22 +3,12 @@ #include <linux/sched.h> #include <linux/hugetlb.h> -/* - * Check the current skip status of page table walker. - * - * Here what I mean by skip is to skip lower level walking, and that was - * determined for each entry independently. For example, when walk_pmd_range - * handles a pmd_trans_huge we don't have to walk over ptes under that pmd, - * and the skipping does not affect the walking over ptes under other pmds. - * That's why we reset @walk->skip after tested. - */ -static bool skip_lower_level_walking(struct mm_walk *walk) +static int get_reset_walk_control(struct mm_walk *walk) { - if (walk->skip) { - walk->skip = 0; - return true; - } - return false; + int ret = walk->control; + /* Reset to default value */ + walk->control = PTWALK_NEXT; + return ret; } static int walk_pte_range(pmd_t *pmd, unsigned long addr, @@ -47,7 +37,18 @@ static int walk_pte_range(pmd_t *pmd, unsigned long addr, err = walk->pte_entry(pte, addr, addr + PAGE_SIZE, walk); if (err) break; + switch (get_reset_walk_control(walk)) { + case PTWALK_NEXT: + continue; + case PTWALK_DOWN: + break; + case PTWALK_BREAK: + goto out_unlock; + default: + BUG(); + } } while (pte++, addr += PAGE_SIZE, addr < end); +out_unlock: pte_unmap_unlock(orig_pte, ptl); cond_resched(); return addr == end ? 0 : err; @@ -75,10 +76,16 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, if (walk->pmd_entry) { err = walk->pmd_entry(pmd, addr, next, walk); - if (skip_lower_level_walking(walk)) - continue; if (err) break; + switch (get_reset_walk_control(walk)) { + case PTWALK_NEXT: + continue; + case PTWALK_DOWN: + break; + default: + BUG(); + } } if (walk->pte_entry) { @@ -204,13 +211,13 @@ static inline int walk_hugetlb_range(unsigned long addr, unsigned long end, #endif /* CONFIG_HUGETLB_PAGE */ /* - * Decide whether we really walk over the current vma on [@start, @end) - * or skip it. When we skip it, we set @walk->skip to 1. - * The return value is used to control the page table walking to - * continue (for zero) or not (for non-zero). + * Decide whether we really walk over the current vma on [@start, @end) or + * skip it. If we walk over it, we should set @walk->control to PTWALK_DOWN. + * Otherwise, we skip it. The return value is used to control the current + * walking to continue (for zero) or terminate (for non-zero). * - * Default check (only VM_PFNMAP check for now) is used when the caller - * doesn't define test_walk() callback. + * We fall through to the default check if the caller doesn't define its own + * test_walk() callback. */ static int walk_page_test(unsigned long start, unsigned long end, struct mm_walk *walk) @@ -224,8 +231,8 @@ static int walk_page_test(unsigned long start, unsigned long end, * Do not walk over vma(VM_PFNMAP), because we have no valid struct * page backing a VM_PFNMAP range. See also commit a9ff785e4437. */ - if (vma->vm_flags & VM_PFNMAP) - walk->skip = 1; + if (!(vma->vm_flags & VM_PFNMAP)) + walk->control = PTWALK_DOWN; return 0; } @@ -266,7 +273,7 @@ static int __walk_page_range(unsigned long start, unsigned long end, * defines test_walk(), pmd_entry(), and pte_entry(), then callbacks are * called in the order of test_walk(), pmd_entry(), and pte_entry(). * If you don't want to go down to lower level at some point and move to - * the next entry in the same level, you set @walk->skip to 1. + * the next entry in the same level, you set @walk->control to PTWALK_DOWN. * For example if you succeed to handle some pmd entry as trans_huge entry, * you need not call walk_pte_range() any more, so set it to avoid that. * We can't determine whether to go down to lower level with the return @@ -310,10 +317,16 @@ int walk_page_range(unsigned long start, unsigned long end, next = min(end, vma->vm_end); err = walk_page_test(start, next, walk); - if (skip_lower_level_walking(walk)) - continue; if (err) break; + switch (get_reset_walk_control(walk)) { + case PTWALK_NEXT: + continue; + case PTWALK_DOWN: + break; + default: + BUG(); + } } err = __walk_page_range(start, next, walk); if (err) @@ -333,9 +346,15 @@ int walk_page_vma(struct vm_area_struct *vma, struct mm_walk *walk) VM_BUG_ON(!vma); walk->vma = vma; err = walk_page_test(vma->vm_start, vma->vm_end, walk); - if (skip_lower_level_walking(walk)) - return 0; if (err) return err; + switch (get_reset_walk_control(walk)) { + case PTWALK_NEXT: + return 0; + case PTWALK_DOWN: + break; + default: + BUG(); + } return __walk_page_range(vma->vm_start, vma->vm_end, walk); } -- 1.9.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
