Messages in this thread Patch in this message | | | From | Yinghai Lu <> | Subject | [PATCH] x86: Fix booting with DEBUG_PAGE_ALLOC with more than 512G RAM | Date | Mon, 12 Aug 2013 16:43:24 -0700 |
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Dave reported that system have early crash if DEBUG_PAGEALLOC is selected, when system have between 500G and 600G.
> [ 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 switch to use #PF handler set mem mapping.
> commit 8170e6bed465b4b0c7687f93e9948aca4358a33b > 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 have 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 extra page for pgd page with [512G, 1024g).
Increase pages in BRK for page table to solve the booting problem.
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> 3.9+
--- arch/x86/mm/init.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
Index: linux-2.6/arch/x86/mm/init.c =================================================================== --- linux-2.6.orig/arch/x86/mm/init.c +++ linux-2.6/arch/x86/mm/init.c @@ -78,8 +78,8 @@ __ref void *alloc_low_pages(unsigned int return __va(pfn << PAGE_SHIFT); } -/* need 4 4k for initial PMD_SIZE, 4k for 0-ISA_END_ADDRESS */ -#define INIT_PGT_BUF_SIZE (5 * PAGE_SIZE) +/* need 3 4k for initial PMD_SIZE, 3 4k for 0-ISA_END_ADDRESS */ +#define INIT_PGT_BUF_SIZE (6 * PAGE_SIZE) RESERVE_BRK(early_pgt_alloc, INIT_PGT_BUF_SIZE); void __init early_alloc_pgt_buf(void) {
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