4.12-rc ppc64 4k-page needs costly allocations
Aneesh Kumar K.V
aneesh.kumar at linux.vnet.ibm.com
Thu Jun 1 14:19:02 AEST 2017
Hugh Dickins <hughd at google.com> writes:
> Since f6eedbba7a26 ("powerpc/mm/hash: Increase VA range to 128TB")
> I find that swapping loads on ppc64 on G5 with 4k pages are failing:
>
> SLUB: Unable to allocate memory on node -1, gfp=0x14000c0(GFP_KERNEL)
> cache: pgtable-2^12, object size: 32768, buffer size: 65536, default order: 4, min order: 4
> pgtable-2^12 debugging increased min order, use slub_debug=O to disable.
> node 0: slabs: 209, objs: 209, free: 8
> gcc: page allocation failure: order:4, mode:0x16040c0(GFP_KERNEL|__GFP_COMP|__GFP_NOTRACK), nodemask=(null)
> CPU: 1 PID: 6225 Comm: gcc Not tainted 4.12.0-rc2 #1
> Call Trace:
> [c00000000090b5c0] [c0000000004f8478] .dump_stack+0xa0/0xcc (unreliable)
> [c00000000090b650] [c0000000000eb194] .warn_alloc+0xf0/0x178
> [c00000000090b710] [c0000000000ebc9c] .__alloc_pages_nodemask+0xa04/0xb00
> [c00000000090b8b0] [c00000000013921c] .new_slab+0x234/0x608
> [c00000000090b980] [c00000000013b59c] .___slab_alloc.constprop.64+0x3dc/0x564
> [c00000000090bad0] [c0000000004f5a84] .__slab_alloc.isra.61.constprop.63+0x54/0x70
> [c00000000090bb70] [c00000000013b864] .kmem_cache_alloc+0x140/0x288
> [c00000000090bc30] [c00000000004d934] .mm_init.isra.65+0x128/0x1c0
> [c00000000090bcc0] [c000000000157810] .do_execveat_common.isra.39+0x294/0x690
> [c00000000090bdb0] [c000000000157e70] .SyS_execve+0x28/0x38
> [c00000000090be30] [c00000000000a118] system_call+0x38/0xfc
>
> I did try booting with slub_debug=O as the message suggested, but that
> made no difference: it still hoped for but failed on order:4 allocations.
>
> I wanted to try removing CONFIG_SLUB_DEBUG, but didn't succeed in that:
> it seemed to be a hard requirement for something, but I didn't find what.
>
> I did try CONFIG_SLAB=y instead of SLUB: that lowers these allocations to
> the expected order:3, which then results in OOM-killing rather than direct
> allocation failure, because of the PAGE_ALLOC_COSTLY_ORDER 3 cutoff. But
> makes no real difference to the outcome: swapping loads still abort early.
>
> Relying on order:3 or order:4 allocations is just too optimistic: ppc64
> with 4k pages would do better not to expect to support a 128TB userspace.
>
> I tried the obvious partial revert below, but it's not good enough:
> the system did not boot beyond
>
> Starting init: /sbin/init exists but couldn't execute it (error -7)
> Starting init: /bin/sh exists but couldn't execute it (error -7)
> Kernel panic - not syncing: No working init found. ...
>
Can you try this patch.
commit fc55c0dc8b23446f937c1315aa61e74673de5ee6
Author: Aneesh Kumar K.V <aneesh.kumar at linux.vnet.ibm.com>
Date: Thu Jun 1 08:06:40 2017 +0530
powerpc/mm/4k: Limit 4k page size to 64TB
Supporting 512TB requires us to do a order 3 allocation for level 1 page
table(pgd). Limit 4k to 64TB for now.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.vnet.ibm.com>
diff --git a/arch/powerpc/include/asm/book3s/64/hash-4k.h b/arch/powerpc/include/asm/book3s/64/hash-4k.h
index b4b5e6b671ca..0c4e470571ca 100644
--- a/arch/powerpc/include/asm/book3s/64/hash-4k.h
+++ b/arch/powerpc/include/asm/book3s/64/hash-4k.h
@@ -8,7 +8,7 @@
#define H_PTE_INDEX_SIZE 9
#define H_PMD_INDEX_SIZE 7
#define H_PUD_INDEX_SIZE 9
-#define H_PGD_INDEX_SIZE 12
+#define H_PGD_INDEX_SIZE 9
#ifndef __ASSEMBLY__
#define H_PTE_TABLE_SIZE (sizeof(pte_t) << H_PTE_INDEX_SIZE)
diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index a2123f291ab0..5de3271026f1 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -110,13 +110,15 @@ void release_thread(struct task_struct *);
#define TASK_SIZE_128TB (0x0000800000000000UL)
#define TASK_SIZE_512TB (0x0002000000000000UL)
-#ifdef CONFIG_PPC_BOOK3S_64
+#if defined(CONFIG_PPC_BOOK3S_64) && defined(CONFIG_PPC_64K_PAGES)
/*
* Max value currently used:
*/
-#define TASK_SIZE_USER64 TASK_SIZE_512TB
+#define TASK_SIZE_USER64 TASK_SIZE_512TB
+#define DEFAULT_MAP_WINDOW_USER64 TASK_SIZE_128TB
#else
-#define TASK_SIZE_USER64 TASK_SIZE_64TB
+#define TASK_SIZE_USER64 TASK_SIZE_64TB
+#define DEFAULT_MAP_WINDOW_USER64 TASK_SIZE_64TB
#endif
/*
@@ -132,7 +134,7 @@ void release_thread(struct task_struct *);
* space during mmap's.
*/
#define TASK_UNMAPPED_BASE_USER32 (PAGE_ALIGN(TASK_SIZE_USER32 / 4))
-#define TASK_UNMAPPED_BASE_USER64 (PAGE_ALIGN(TASK_SIZE_128TB / 4))
+#define TASK_UNMAPPED_BASE_USER64 (PAGE_ALIGN(DEFAULT_MAP_WINDOW_USER64 / 4))
#define TASK_UNMAPPED_BASE ((is_32bit_task()) ? \
TASK_UNMAPPED_BASE_USER32 : TASK_UNMAPPED_BASE_USER64 )
@@ -143,8 +145,8 @@ void release_thread(struct task_struct *);
* with 128TB and conditionally enable upto 512TB
*/
#ifdef CONFIG_PPC_BOOK3S_64
-#define DEFAULT_MAP_WINDOW ((is_32bit_task()) ? \
- TASK_SIZE_USER32 : TASK_SIZE_128TB)
+#define DEFAULT_MAP_WINDOW ((is_32bit_task()) ? \
+ TASK_SIZE_USER32 : DEFAULT_MAP_WINDOW_USER64)
#else
#define DEFAULT_MAP_WINDOW TASK_SIZE
#endif
@@ -153,7 +155,7 @@ void release_thread(struct task_struct *);
#ifdef CONFIG_PPC_BOOK3S_64
/* Limit stack to 128TB */
-#define STACK_TOP_USER64 TASK_SIZE_128TB
+#define STACK_TOP_USER64 DEFAULT_MAP_WINDOW_USER64
#else
#define STACK_TOP_USER64 TASK_SIZE_USER64
#endif
diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c
index 8389ff5ac002..77062461c469 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -921,7 +921,7 @@ void __init setup_arch(char **cmdline_p)
#ifdef CONFIG_PPC_MM_SLICES
#ifdef CONFIG_PPC64
- init_mm.context.addr_limit = TASK_SIZE_128TB;
+ init_mm.context.addr_limit = DEFAULT_MAP_WINDOW_USER64;
#else
#error "context.addr_limit not initialized."
#endif
diff --git a/arch/powerpc/mm/mmu_context_book3s64.c b/arch/powerpc/mm/mmu_context_book3s64.c
index c6dca2ae78ef..a3edf813d455 100644
--- a/arch/powerpc/mm/mmu_context_book3s64.c
+++ b/arch/powerpc/mm/mmu_context_book3s64.c
@@ -99,7 +99,7 @@ static int hash__init_new_context(struct mm_struct *mm)
* mm->context.addr_limit. Default to max task size so that we copy the
* default values to paca which will help us to handle slb miss early.
*/
- mm->context.addr_limit = TASK_SIZE_128TB;
+ mm->context.addr_limit = DEFAULT_MAP_WINDOW_USER64;
/*
* The old code would re-promote on fork, we don't do that when using
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