Dave Hansen reported that systems between 500G and 600G RAM
crash early if DEBUG_PAGEALLOC is selected.
> [ 0.000000] init_memory_mapping: [mem 0x00000000-0x000fffff]
> [ 0.000000] [mem 0x00000000-0x000fffff] page 4k
> [ 0.000000] BRK [0x02086000, 0x02086fff] PGTABLE
> [ 0.000000] BRK [0x02087000, 0x02087fff] PGTABLE
> [ 0.000000] BRK [0x02088000, 0x02088fff] PGTABLE
> [ 0.000000] init_memory_mapping: [mem 0xe80ee00000-0xe80effffff]
> [ 0.000000] [mem 0xe80ee00000-0xe80effffff] page 4k
> [ 0.000000] BRK [0x02089000, 0x02089fff] PGTABLE
> [ 0.000000] BRK [0x0208a000, 0x0208afff] PGTABLE
> [ 0.000000] Kernel panic - not syncing: alloc_low_page: ran out of memory
It turns out that we missed increasing needed pages in BRK to
mapping initial 2M and [0,1M) when we switched to use the #PF
handler to set memory mappings:
> commit 8170e6bed4
> Author: H. Peter Anvin <hpa@zytor.com>
> Date: Thu Jan 24 12:19:52 2013 -0800
>
> x86, 64bit: Use a #PF handler to materialize early mappings on demand
Before that, we had the maping from [0,512M) in head_64.S, and we
can spare two pages [0-1M). After that change, we can not reuse
pages anymore.
When we have more than 512M ram, we need an extra page for pgd page
with [512G, 1024g).
Increase pages in BRK for page table to solve the boot crash.
Reported-by: Dave Hansen <dave.hansen@intel.com>
Bisected-by: Dave Hansen <dave.hansen@intel.com>
Tested-by: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: <stable@vger.kernel.org> # v3.9 and later
Link: http://lkml.kernel.org/r/1376351004-4015-1-git-send-email-yinghai@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
527bf129f9