Re: 4.12-rc ppc64 4k-page needs costly allocations
From: Hugh Dickins <hughd@google.com>
Date: 2017-06-01 16:57:42
Also in:
linux-mm
On Thu, 1 Jun 2017, Aneesh Kumar K.V wrote:
Hugh Dickins [off-list ref] writes:quoted
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.
Thanks! By the time I got to try it, you'd sent another later in the day. Fractionally different, and I didn't spend any time working out whether the difference was significant or cosmetic, I just tried that second one instead. No problems with it so far, hasn't been running long, but long enough to say that it definitely fixes the problems I was getting - thank you. Hugh
quoted hunk ↗ jump to hunk
commit fc55c0dc8b23446f937c1315aa61e74673de5ee6 Author: Aneesh Kumar K.V [off-list ref] 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 [off-list ref]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 #endifdiff --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." #endifdiff --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