The patch titled
Subject: mm: hugetlb: introduce page_huge_active
has been removed from the -mm tree. Its filename was
mm-hugetlb-introduce-pagehugeactive-flag.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Subject: mm: hugetlb: introduce page_huge_active
We are not safe from calling isolate_huge_page() on a hugepage
concurrently, which can make the victim hugepage in invalid state and
results in BUG_ON().
The root problem of this is that we don't have any information on struct
page (so easily accessible) about hugepages' activeness. Note that
hugepages' activeness means just being linked to
hstate->hugepage_activelist, which is not the same as normal pages'
activeness represented by PageActive flag.
Normal pages are isolated by isolate_lru_page() which prechecks PageLRU
before isolation, so let's do similarly for hugetlb with a new
paeg_huge_active().
set/clear_page_huge_active() should be called within hugetlb_lock. But
hugetlb_cow() and hugetlb_no_page() don't do this, being justified because
in these functions set_page_huge_active() is called right after the
hugepage is allocated and no other thread tries to isolate it.
[akpm@xxxxxxxxxxxxxxxxxxxx: s/PageHugeActive/page_huge_active/, make it return bool]
[fengguang.wu@xxxxxxxxx: set_page_huge_active() can be static]
Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Reviewed-by: Michal Hocko <mhocko@xxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Fengguang Wu <fengguang.wu@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/hugetlb.c | 41 ++++++++++++++++++++++++++++++++++++++---
mm/memory-failure.c | 14 ++++++++++++--
2 files changed, 50 insertions(+), 5 deletions(-)
diff -puN mm/hugetlb.c~mm-hugetlb-introduce-pagehugeactive-flag mm/hugetlb.c
--- a/mm/hugetlb.c~mm-hugetlb-introduce-pagehugeactive-flag
+++ a/mm/hugetlb.c
@@ -924,6 +924,31 @@ struct hstate *size_to_hstate(unsigned l
return NULL;
}
+/*
+ * Test to determine whether the hugepage is "active/in-use" (i.e. being linked
+ * to hstate->hugepage_activelist.)
+ *
+ * This function can be called for tail pages, but never returns true for them.
+ */
+bool page_huge_active(struct page *page)
+{
+ VM_BUG_ON_PAGE(!PageHuge(page), page);
+ return PageHead(page) && PagePrivate(&page[1]);
+}
+
+/* never called for tail page */
+static void set_page_huge_active(struct page *page)
+{
+ VM_BUG_ON_PAGE(!PageHeadHuge(page), page);
+ SetPagePrivate(&page[1]);
+}
+
+static void clear_page_huge_active(struct page *page)
+{
+ VM_BUG_ON_PAGE(!PageHeadHuge(page), page);
+ ClearPagePrivate(&page[1]);
+}
+
void free_huge_page(struct page *page)
{
/*
@@ -952,6 +977,7 @@ void free_huge_page(struct page *page)
restore_reserve = true;
spin_lock(&hugetlb_lock);
+ clear_page_huge_active(page);
hugetlb_cgroup_uncharge_page(hstate_index(h),
pages_per_huge_page(h), page);
if (restore_reserve)
@@ -2972,6 +2998,7 @@ retry_avoidcopy:
copy_user_huge_page(new_page, old_page, address, vma,
pages_per_huge_page(h));
__SetPageUptodate(new_page);
+ set_page_huge_active(new_page);
mmun_start = address & huge_page_mask(h);
mmun_end = mmun_start + huge_page_size(h);
@@ -3084,6 +3111,7 @@ retry:
}
clear_huge_page(page, address, pages_per_huge_page(h));
__SetPageUptodate(page);
+ set_page_huge_active(page);
if (vma->vm_flags & VM_MAYSHARE) {
int err;
@@ -3913,19 +3941,26 @@ int dequeue_hwpoisoned_huge_page(struct
bool isolate_huge_page(struct page *page, struct list_head *list)
{
+ bool ret = true;
+
VM_BUG_ON_PAGE(!PageHead(page), page);
- if (!get_page_unless_zero(page))
- return false;
spin_lock(&hugetlb_lock);
+ if (!page_huge_active(page) || !get_page_unless_zero(page)) {
+ ret = false;
+ goto unlock;
+ }
+ clear_page_huge_active(page);
list_move_tail(&page->lru, list);
+unlock:
spin_unlock(&hugetlb_lock);
- return true;
+ return ret;
}
void putback_active_hugepage(struct page *page)
{
VM_BUG_ON_PAGE(!PageHead(page), page);
spin_lock(&hugetlb_lock);
+ set_page_huge_active(page);
list_move_tail(&page->lru, &(page_hstate(page))->hugepage_activelist);
spin_unlock(&hugetlb_lock);
put_page(page);
diff -puN mm/memory-failure.c~mm-hugetlb-introduce-pagehugeactive-flag mm/memory-failure.c
--- a/mm/memory-failure.c~mm-hugetlb-introduce-pagehugeactive-flag
+++ a/mm/memory-failure.c
@@ -1586,8 +1586,18 @@ static int soft_offline_huge_page(struct
}
unlock_page(hpage);
- /* Keep page count to indicate a given hugepage is isolated. */
- list_move(&hpage->lru, &pagelist);
+ ret = isolate_huge_page(hpage, &pagelist);
+ if (ret) {
+ /*
+ * get_any_page() and isolate_huge_page() takes a refcount each,
+ * so need to drop one here.
+ */
+ put_page(hpage);
+ } else {
+ pr_info("soft offline: %#lx hugepage failed to isolate\n", pfn);
+ return -EBUSY;
+ }
+
ret = migrate_pages(&pagelist, new_page, NULL, MPOL_MF_MOVE_ALL,
MIGRATE_SYNC, MR_MEMORY_FAILURE);
if (ret) {
_
Patches currently in -mm which might be from n-horiguchi@xxxxxxxxxxxxx are
origin.patch
page-flags-trivial-cleanup-for-pagetrans-helpers.patch
page-flags-introduce-page-flags-policies-wrt-compound-pages.patch
page-flags-define-pg_locked-behavior-on-compound-pages.patch
page-flags-define-behavior-of-fs-io-related-flags-on-compound-pages.patch
page-flags-define-behavior-of-lru-related-flags-on-compound-pages.patch
page-flags-define-behavior-slb-related-flags-on-compound-pages.patch
page-flags-define-behavior-of-xen-related-flags-on-compound-pages.patch
page-flags-define-pg_reserved-behavior-on-compound-pages.patch
page-flags-define-pg_swapbacked-behavior-on-compound-pages.patch
page-flags-define-pg_swapcache-behavior-on-compound-pages.patch
page-flags-define-pg_mlocked-behavior-on-compound-pages.patch
page-flags-define-pg_uncached-behavior-on-compound-pages.patch
page-flags-define-pg_uptodate-behavior-on-compound-pages.patch
page-flags-look-on-head-page-if-the-flag-is-encoded-in-page-mapping.patch
mm-sanitize-page-mapping-for-tail-pages.patch
do_shared_fault-check-that-mmap_sem-is-held.patch
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