On Mon, Sep 28, 2015 at 01:02:19PM +0300, Konstantin Khlebnikov wrote: > On 25.09.2015 22:13, Kirill A. Shutemov wrote: > >On Fri, Sep 25, 2015 at 03:29:17PM +0300, Konstantin Khlebnikov wrote: > >>On 24.09.2015 17:50, Kirill A. Shutemov wrote: > >>>This patch adds a third argument to macros which create function > >>>definitions for page flags. This argument defines how page-flags helpers > >>>behave on compound functions. > >>> > >>>For now we define four policies: > >>> > >>>- PF_ANY: the helper function operates on the page it gets, regardless > >>> if it's non-compound, head or tail. > >>> > >>>- PF_HEAD: the helper function operates on the head page of the compound > >>> page if it gets tail page. > >>> > >>>- PF_NO_TAIL: only head and non-compond pages are acceptable for this > >>> helper function. > >>> > >>>- PF_NO_COMPOUND: only non-compound pages are acceptable for this helper > >>> function. > >>> > >>>For now we use policy PF_ANY for all helpers, which matches current > >>>behaviour. > >>> > >>>We do not enforce the policy for TESTPAGEFLAG, because we have flags > >>>checked for random pages all over the kernel. Noticeable exception to > >>>this is PageTransHuge() which triggers VM_BUG_ON() for tail page. > >>> > >>>Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> > >>>--- > >>> include/linux/page-flags.h | 154 ++++++++++++++++++++++++++------------------- > >>> 1 file changed, 90 insertions(+), 64 deletions(-) > >>> > >>>diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h > >>>index 713d3f2c2468..1b3babe5ff69 100644 > >>>--- a/include/linux/page-flags.h > >>>+++ b/include/linux/page-flags.h > >>>@@ -154,49 +154,68 @@ static inline int PageCompound(struct page *page) > >>> return test_bit(PG_head, &page->flags) || PageTail(page); > >>> } > >>> > >>>+/* Page flags policies wrt compound pages */ > >>>+#define PF_ANY(page, enforce) page > >>>+#define PF_HEAD(page, enforce) compound_head(page) > >>>+#define PF_NO_TAIL(page, enforce) ({ \ > >>>+ if (enforce) \ > >>>+ VM_BUG_ON_PAGE(PageTail(page), page); \ > >>>+ else \ > >>>+ page = compound_head(page); \ > >>>+ page;}) > >>>+#define PF_NO_COMPOUND(page, enforce) ({ \ > >>>+ if (enforce) \ > >>>+ VM_BUG_ON_PAGE(PageCompound(page), page); \ > >> > >>Linux next-20150925 crashes here (at least in lkvm) > >>if CONFIG_DEFERRED_STRUCT_PAGE_INIT=y > > > >Hm. I don't see the crash in qemu. Could you share your config? > > see in attachment Still don't see it. Have you tried patch from my previous mail? -- Kirill A. Shutemov -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>