From 7de3d66b1387ddf5a37d9689e5eb8510fb75c765 Mon Sep 17 00:00:00 2001 From: Yinghai Lu Date: Fri, 31 May 2013 08:53:07 -0700 Subject: x86: Fix adjust_range_size_mask calling position Commit 8d57470d x86, mm: setup page table in top-down causes a kernel panic while setting mem=2G. [mem 0x00000000-0x000fffff] page 4k [mem 0x7fe00000-0x7fffffff] page 1G [mem 0x7c000000-0x7fdfffff] page 1G [mem 0x00100000-0x001fffff] page 4k [mem 0x00200000-0x7bffffff] page 2M for last entry is not what we want, we should have [mem 0x00200000-0x3fffffff] page 2M [mem 0x40000000-0x7bffffff] page 1G Actually we merge the continuous ranges with same page size too early. in this case, before merging we have [mem 0x00200000-0x3fffffff] page 2M [mem 0x40000000-0x7bffffff] page 2M after merging them, will get [mem 0x00200000-0x7bffffff] page 2M even we can use 1G page to map [mem 0x40000000-0x7bffffff] that will cause problem, because we already map [mem 0x7fe00000-0x7fffffff] page 1G [mem 0x7c000000-0x7fdfffff] page 1G with 1G page, aka [0x40000000-0x7fffffff] is mapped with 1G page already. During phys_pud_init() for [0x40000000-0x7bffffff], it will not reuse existing that pud page, and allocate new one then try to use 2M page to map it instead, as page_size_mask does not include PG_LEVEL_1G. At end will have [7c000000-0x7fffffff] not mapped, loop in phys_pmd_init stop mapping at 0x7bffffff. That is right behavoir, it maps exact range with exact page size that we ask, and we should explicitly call it to map [7c000000-0x7fffffff] before or after mapping 0x40000000-0x7bffffff. Anyway we need to make sure ranges' page_size_mask correct and consistent after split_mem_range for each range. Fix that by calling adjust_range_size_mask before merging range with same page size. -v2: update change log. -v3: add more explanation why [7c000000-0x7fffffff] is not mapped, and it causes panic. Bisected-by: "Xie, ChanglongX" Bisected-by: Yuanhan Liu Reported-and-tested-by: Yuanhan Liu Signed-off-by: Yinghai Lu Link: http://lkml.kernel.org/r/1370015587-20835-1-git-send-email-yinghai@kernel.org Cc: v3.9 Signed-off-by: H. Peter Anvin --- arch/x86/mm/init.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'arch') diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index eaac1743def7..1f34e9219775 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -277,6 +277,9 @@ static int __meminit split_mem_range(struct map_range *mr, int nr_range, end_pfn = limit_pfn; nr_range = save_mr(mr, nr_range, start_pfn, end_pfn, 0); + if (!after_bootmem) + adjust_range_page_size_mask(mr, nr_range); + /* try to merge same page size and continuous */ for (i = 0; nr_range > 1 && i < nr_range - 1; i++) { unsigned long old_start; @@ -291,9 +294,6 @@ static int __meminit split_mem_range(struct map_range *mr, int nr_range, nr_range--; } - if (!after_bootmem) - adjust_range_page_size_mask(mr, nr_range); - for (i = 0; i < nr_range; i++) printk(KERN_DEBUG " [mem %#010lx-%#010lx] page %s\n", mr[i].start, mr[i].end - 1, -- cgit v1.2.3