Hi Alexandru, On Tue, Sep 12, 2017 at 10:43:06PM +0200, Alexandru Moise wrote: > This fixes a bug in madvise() where if you'd try to soft offline a > hugepage via madvise(), while walking the address range you'd end up, > using the wrong page offset due to attempting to get the compound > order of a former but presently not compound page, due to dissolving > the huge page (since c3114a8). > > Signed-off-by: Alexandru Moise <00moses.alexande...@gmail.com>
There was a similar discussion in https://marc.info/?l=linux-kernel&m=150354919510631&w=2 over thp. As I stated there, if we give multi-page range into the parameters [start, end), we expect that memory errors are injected to every single page within the range. So I start to feel that we should revert the following patch which introduced the multi-page stepping. commit 20cb6cab52a21b46e3c0dc7bd23f004f810fb421 Author: Wanpeng Li <liw...@linux.vnet.ibm.com> Date: Mon Sep 30 13:45:21 2013 -0700 mm/hwpoison: fix traversal of hugetlbfs pages to avoid printk flood In order to suppress the printk flood, we can use ratelimit mechanism, or just s/pr_info/pr_debug/ might be ok. Thanks, Naoya Horiguchi > --- > mm/madvise.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/mm/madvise.c b/mm/madvise.c > index 21261ff0466f..25bade36e9ca 100644 > --- a/mm/madvise.c > +++ b/mm/madvise.c > @@ -625,18 +625,26 @@ static int madvise_inject_error(int behavior, > { > struct page *page; > struct zone *zone; > + unsigned int order; > > if (!capable(CAP_SYS_ADMIN)) > return -EPERM; > > - for (; start < end; start += PAGE_SIZE << > - compound_order(compound_head(page))) { > + > + for (; start < end; start += PAGE_SIZE << order) { > int ret; > > ret = get_user_pages_fast(start, 1, 0, &page); > if (ret != 1) > return ret; > > + /* > + * When soft offlining hugepages, after migrating the page > + * we dissolve it, therefore in the second loop "page" will > + * no longer be a compound page, and order will be 0. > + */ > + order = compound_order(compound_head(page)); > + > if (PageHWPoison(page)) { > put_page(page); > continue; > -- > 2.14.1 > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majord...@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"d...@kvack.org";> em...@kvack.org </a>
