Commit 527bf129 authored by Yinghai Lu's avatar Yinghai Lu Committed by Ingo Molnar

x86/mm: Fix boot crash with DEBUG_PAGE_ALLOC=y and more than 512G RAM

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 8170e6be
 > 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: default avatarDave Hansen <dave.hansen@intel.com>
Bisected-by: default avatarDave Hansen <dave.hansen@intel.com>
Tested-by: default avatarDave Hansen <dave.hansen@intel.com>
Signed-off-by: default avatarYinghai 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.orgSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent fd3930f7
...@@ -78,8 +78,8 @@ __ref void *alloc_low_pages(unsigned int num) ...@@ -78,8 +78,8 @@ __ref void *alloc_low_pages(unsigned int num)
return __va(pfn << PAGE_SHIFT); return __va(pfn << PAGE_SHIFT);
} }
/* need 4 4k for initial PMD_SIZE, 4k for 0-ISA_END_ADDRESS */ /* need 3 4k for initial PMD_SIZE, 3 4k for 0-ISA_END_ADDRESS */
#define INIT_PGT_BUF_SIZE (5 * PAGE_SIZE) #define INIT_PGT_BUF_SIZE (6 * PAGE_SIZE)
RESERVE_BRK(early_pgt_alloc, INIT_PGT_BUF_SIZE); RESERVE_BRK(early_pgt_alloc, INIT_PGT_BUF_SIZE);
void __init early_alloc_pgt_buf(void) void __init early_alloc_pgt_buf(void)
{ {
......
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