Messages in this thread Patch in this message | | | Subject | Re: [GIT PULL v2] Early SLAB fixes for 2.6.31 | From | Benjamin Herrenschmidt <> | Date | Thu, 18 Jun 2009 13:24:12 +1000 |
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On Thu, 2009-06-18 at 12:00 +1000, Benjamin Herrenschmidt wrote: > > So I'm very much ok with the whole "use magic gfp_mask to indicate what > > works at what stage". And yes, I think it makes sense to extend it to the > > page allocator and might_sleep too, because GFP_KERNEL has all the same > > issues regardless of whether it's about page allocation or about slab > > allocators. And any "might_sleep" suppression really does tend to be about > > the exact same thing. > > Argh... still broken. > > In fact, my initial patch added it to the page allocator, which worked > for me. Pekka patch removed that and made it slab-only. So I'm blowing > up at boot in lockdep or so because I'm allocating page tables on > ppc32 with __get_free_pages() and GFP_KERNEL. > > I'll cook up a patch.
Here it is:
mm: Extend gfp masking to the page allocator
The page allocator also needs the masking of gfp flags during boot, so this moves it out of slab/slub and uses it with the page allocator as well.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> ---
This will also make it easier to use it for limiting allocations that can block during suspend/resume, though doing this really fool-proof will require some kind of synchronization in set_gfp_allowed_mask() vs. allocations that have already started sleeping waiting for IOs.
Index: linux-work/include/linux/gfp.h =================================================================== --- linux-work.orig/include/linux/gfp.h 2009-06-18 12:03:14.000000000 +1000 +++ linux-work/include/linux/gfp.h 2009-06-18 12:08:21.000000000 +1000 @@ -99,7 +99,7 @@ struct vm_area_struct; __GFP_NORETRY|__GFP_NOMEMALLOC) /* Control slab gfp mask during early boot */ -#define SLAB_GFP_BOOT_MASK __GFP_BITS_MASK & ~(__GFP_WAIT|__GFP_IO|__GFP_FS) +#define GFP_BOOT_MASK __GFP_BITS_MASK & ~(__GFP_WAIT|__GFP_IO|__GFP_FS) /* Control allocation constraints */ #define GFP_CONSTRAINT_MASK (__GFP_HARDWALL|__GFP_THISNODE) @@ -348,4 +348,11 @@ static inline void oom_killer_enable(voi oom_killer_disabled = false; } +extern gfp_t gfp_allowed_mask; + +static inline void set_gfp_allowed_mask(gfp_t mask) +{ + gfp_allowed_mask = mask; +} + #endif /* __LINUX_GFP_H */ Index: linux-work/init/main.c =================================================================== --- linux-work.orig/init/main.c 2009-06-18 12:06:49.000000000 +1000 +++ linux-work/init/main.c 2009-06-18 12:08:35.000000000 +1000 @@ -642,6 +642,10 @@ asmlinkage void __init start_kernel(void "enabled early\n"); early_boot_irqs_on(); local_irq_enable(); + + /* Interrupts are enabled now so all GFP allocations are safe. */ + set_gfp_allowed_mask(__GFP_BITS_MASK); + kmem_cache_init_late(); /* Index: linux-work/mm/page_alloc.c =================================================================== --- linux-work.orig/mm/page_alloc.c 2009-06-18 12:04:58.000000000 +1000 +++ linux-work/mm/page_alloc.c 2009-06-18 12:09:27.000000000 +1000 @@ -73,6 +73,7 @@ unsigned long totalram_pages __read_most unsigned long totalreserve_pages __read_mostly; unsigned long highest_memmap_pfn __read_mostly; int percpu_pagelist_fraction; +gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK; #ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE int pageblock_order __read_mostly; @@ -1863,6 +1864,8 @@ __alloc_pages_nodemask(gfp_t gfp_mask, u struct page *page; int migratetype = allocflags_to_migratetype(gfp_mask); + gfp_mask &= gfp_allowed_mask; + lockdep_trace_alloc(gfp_mask); might_sleep_if(gfp_mask & __GFP_WAIT); Index: linux-work/mm/slab.c =================================================================== --- linux-work.orig/mm/slab.c 2009-06-18 12:05:47.000000000 +1000 +++ linux-work/mm/slab.c 2009-06-18 12:06:19.000000000 +1000 @@ -305,12 +305,6 @@ struct kmem_list3 { }; /* - * The slab allocator is initialized with interrupts disabled. Therefore, make - * sure early boot allocations don't accidentally enable interrupts. - */ -static gfp_t slab_gfp_mask __read_mostly = SLAB_GFP_BOOT_MASK; - -/* * Need this for bootstrapping a per node allocator. */ #define NUM_INIT_LISTS (3 * MAX_NUMNODES) @@ -1559,11 +1553,6 @@ void __init kmem_cache_init_late(void) { struct kmem_cache *cachep; - /* - * Interrupts are enabled now so all GFP allocations are safe. - */ - slab_gfp_mask = __GFP_BITS_MASK; - /* 6) resize the head arrays to their final sizes */ mutex_lock(&cache_chain_mutex); list_for_each_entry(cachep, &cache_chain, next) @@ -3307,7 +3296,7 @@ __cache_alloc_node(struct kmem_cache *ca unsigned long save_flags; void *ptr; - flags &= slab_gfp_mask; + flags &= gfp_allowed_mask; lockdep_trace_alloc(flags); @@ -3392,7 +3381,7 @@ __cache_alloc(struct kmem_cache *cachep, unsigned long save_flags; void *objp; - flags &= slab_gfp_mask; + flags &= gfp_allowed_mask; lockdep_trace_alloc(flags); Index: linux-work/mm/slub.c =================================================================== --- linux-work.orig/mm/slub.c 2009-06-18 12:02:46.000000000 +1000 +++ linux-work/mm/slub.c 2009-06-18 12:06:35.000000000 +1000 @@ -179,12 +179,6 @@ static enum { SYSFS /* Sysfs up */ } slab_state = DOWN; -/* - * The slab allocator is initialized with interrupts disabled. Therefore, make - * sure early boot allocations don't accidentally enable interrupts. - */ -static gfp_t slab_gfp_mask __read_mostly = SLAB_GFP_BOOT_MASK; - /* A list of all slab caches on the system */ static DECLARE_RWSEM(slub_lock); static LIST_HEAD(slab_caches); @@ -1692,7 +1686,7 @@ static __always_inline void *slab_alloc( unsigned long flags; unsigned int objsize; - gfpflags &= slab_gfp_mask; + gfpflags &= gfp_allowed_mask; lockdep_trace_alloc(gfpflags); might_sleep_if(gfpflags & __GFP_WAIT); @@ -3220,10 +3214,6 @@ void __init kmem_cache_init(void) void __init kmem_cache_init_late(void) { - /* - * Interrupts are enabled now so all GFP allocations are safe. - */ - slab_gfp_mask = __GFP_BITS_MASK; } /*
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