On Mon, Mar 16, 2015 at 11:29:45AM -0700, Laura Abbott wrote: > Commit 3c605096d315 ("mm/page_alloc: restrict max order of merging on > isolated pageblock") > changed the logic of unset_migratetype_isolate to check the buddy allocator > and explicitly call __free_pages to merge. The page that is being freed in > this path never had prep_new_page called so set_page_refcounted is called > explicitly but there is no call to kernel_map_pages. With the default > kernel_map_pages this is mostly harmless but if kernel_map_pages does any > manipulation of the page tables (unmapping or setting pages to read only) this > may trigger a fault: > > alloc_contig_range test_pages_isolated(ceb00, ced00) failed > Unable to handle kernel paging request at virtual address ffffffc0cec00000 > pgd = ffffffc045fc4000 > [ffffffc0cec00000] *pgd=0000000000000000 > Internal error: Oops: 9600004f [#1] PREEMPT SMP > Modules linked in: exfatfs > CPU: 1 PID: 23237 Comm: TimedEventQueue Not tainted > 3.10.49-gc72ad36-dirty #1 > task: ffffffc03de52100 ti: ffffffc015388000 task.ti: ffffffc015388000 > PC is at memset+0xc8/0x1c0 > LR is at kernel_map_pages+0x1ec/0x244 > > Fix this by calling kernel_map_pages to ensure the page is set in the > page table properly > > Fixes: 3c605096d315 ("mm/page_alloc: restrict max order of merging on > isolated pageblock") > Cc: Naoya Horiguchi <n-horigu...@ah.jp.nec.com> > Cc: Mel Gorman <mgor...@suse.de> > Cc: Rik van Riel <r...@redhat.com> > Cc: Yasuaki Ishimatsu <isimatu.yasu...@jp.fujitsu.com> > Cc: Zhang Yanfei <zhangyan...@cn.fujitsu.com> > Cc: Xishi Qiu <qiuxi...@huawei.com> > Cc: Vladimir Davydov <vdavy...@parallels.com> > Cc: Joonsoo Kim <iamjoonsoo....@lge.com> > Cc: Gioh Kim <gioh....@lge.com> > Cc: Michal Nazarewicz <min...@mina86.com> > Cc: Marek Szyprowski <m.szyprow...@samsung.com> > Cc: Vlastimil Babka <vba...@suse.cz> > Signed-off-by: Laura Abbott <lau...@codeaurora.org> > --- > Note this was found on a backport to 3.10 and the code to make > kernel_map_pages > change the page table state is currently out of tree. The original had stable, > so this may need to go into stable as well.
I found that some implementation of kernel_map_pages() in mainline also require this change. Some implementation doesn't check previous state of page table, but some others check previous state of page table when calling kernel_map_pages(). Acked-by: Joonsoo Kim <iamjoonsoo....@lge.com> Thanks. > --- > mm/page_isolation.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/mm/page_isolation.c b/mm/page_isolation.c > index 72f5ac3..755a42c 100644 > --- a/mm/page_isolation.c > +++ b/mm/page_isolation.c > @@ -103,6 +103,7 @@ void unset_migratetype_isolate(struct page *page, > unsigned migratetype) > > if (!is_migrate_isolate_page(buddy)) { > __isolate_free_page(page, order); > + kernel_map_pages(page, (1 << order), 1); > set_page_refcounted(page); > isolated_page = page; > } > -- > Qualcomm Innovation Center, Inc. > Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux > Foundation Collaborative Project > This e-mail address will be inactive after March 20, 2015 > Please contact privately for follow up after that date. > > -- > 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> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/