Commit 7de3d66b authored by Yinghai Lu's avatar Yinghai Lu Committed by H. Peter Anvin

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: default avatar"Xie, ChanglongX" <changlongx.xie@intel.com>
Bisected-by: default avatarYuanhan Liu <yuanhan.liu@linux.intel.com>
Reported-and-tested-by: default avatarYuanhan Liu <yuanhan.liu@linux.intel.com>
Signed-off-by: default avatarYinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1370015587-20835-1-git-send-email-yinghai@kernel.org
Cc: <stable@vger.kernel.org> v3.9
Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent a93cb29a
...@@ -277,6 +277,9 @@ static int __meminit split_mem_range(struct map_range *mr, int nr_range, ...@@ -277,6 +277,9 @@ static int __meminit split_mem_range(struct map_range *mr, int nr_range,
end_pfn = limit_pfn; end_pfn = limit_pfn;
nr_range = save_mr(mr, nr_range, start_pfn, end_pfn, 0); 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 */ /* try to merge same page size and continuous */
for (i = 0; nr_range > 1 && i < nr_range - 1; i++) { for (i = 0; nr_range > 1 && i < nr_range - 1; i++) {
unsigned long old_start; unsigned long old_start;
...@@ -291,9 +294,6 @@ static int __meminit split_mem_range(struct map_range *mr, int nr_range, ...@@ -291,9 +294,6 @@ static int __meminit split_mem_range(struct map_range *mr, int nr_range,
nr_range--; nr_range--;
} }
if (!after_bootmem)
adjust_range_page_size_mask(mr, nr_range);
for (i = 0; i < nr_range; i++) for (i = 0; i < nr_range; i++)
printk(KERN_DEBUG " [mem %#010lx-%#010lx] page %s\n", printk(KERN_DEBUG " [mem %#010lx-%#010lx] page %s\n",
mr[i].start, mr[i].end - 1, mr[i].start, mr[i].end - 1,
......
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