| Message ID | 20210526234115.0YhW-QUsd%akpm@linux-foundation.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | + mm-page_alloc-fix-counting-of-free-pages-after-take-off-from-buddy.patch added to -mm tree | expand |
--- a/mm/page_alloc.c~mm-page_alloc-fix-counting-of-free-pages-after-take-off-from-buddy +++ a/mm/page_alloc.c @@ -9158,6 +9158,8 @@ bool take_page_off_buddy(struct page *pa del_page_from_free_list(page_head, zone, page_order); break_down_buddy_pages(zone, page_head, page, 0, page_order, migratetype); + if (!is_migrate_isolate(migratetype)) + __mod_zone_freepage_state(zone, -1, migratetype); ret = true; break; }
The patch titled Subject: mm/page_alloc: fix counting of free pages after take off from buddy has been added to the -mm tree. Its filename is mm-page_alloc-fix-counting-of-free-pages-after-take-off-from-buddy.patch This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/mm-page_alloc-fix-counting-of-free-pages-after-take-off-from-buddy.patch and later at https://ozlabs.org/~akpm/mmotm/broken-out/mm-page_alloc-fix-counting-of-free-pages-after-take-off-from-buddy.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Ding Hui <dinghui@sangfor.com.cn> Subject: mm/page_alloc: fix counting of free pages after take off from buddy Recently we found that there is a lot MemFree left in /proc/meminfo after do a lot of pages soft offline, it's not quite correct. Before Oscar rework soft offline for free pages [1], if we soft offline free pages, these pages are left in buddy with HWPoison flag, and NR_FREE_PAGES is not updated immediately. So the difference between NR_FREE_PAGES and real number of available free pages is also even big at the beginning. However, with the workload running, when we catch HWPoison page in any alloc functions subsequently, we will remove it from buddy, meanwhile update the NR_FREE_PAGES and try again, so the NR_FREE_PAGES will get more and more closer to the real number of available free pages. (regardless of unpoison_memory()) Now, for offline free pages, after a successful call take_page_off_buddy(), the page is no longer belong to buddy allocator, and will not be used any more, but we missed accounting NR_FREE_PAGES in this situation, and there is no chance to be updated later. Do update in take_page_off_buddy() like rmqueue() does, but avoid double counting if some one already set_migratetype_isolate() on the page. [1]: commit 06be6ff3d2ec ("mm,hwpoison: rework soft offline for free pages") Link: https://lkml.kernel.org/r/20210526075247.11130-1-dinghui@sangfor.com.cn Fixes: 06be6ff3d2ec ("mm,hwpoison: rework soft offline for free pages") Signed-off-by: Ding Hui <dinghui@sangfor.com.cn> Suggested-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Acked-by: David Hildenbrand <david@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> --- mm/page_alloc.c | 2 ++ 1 file changed, 2 insertions(+)