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473738eb78
Patch series "mm: give __GFP_REPEAT a better semantic".
The main motivation for the change is that the current implementation of
__GFP_REPEAT is not very much useful.
The documentation says:
* __GFP_REPEAT: Try hard to allocate the memory, but the allocation attempt
* _might_ fail. This depends upon the particular VM implementation.
It just fails to mention that this is true only for large (costly) high
order which has been the case since the flag was introduced. A similar
semantic would be really helpful for smal orders as well, though,
because we have places where a failure with a specific fallback error
handling is preferred to a potential endless loop inside the page
allocator.
The earlier cleanup dropped __GFP_REPEAT usage for low (!costly) order
users so only those which might use larger orders have stayed. One new
user added in the meantime is addressed in patch 1.
Let's rename the flag to something more verbose and use it for existing
users. Semantic for those will not change. Then implement low
(!costly) orders failure path which is hit after the page allocator is
about to invoke the oom killer. With that we have a good counterpart
for __GFP_NORETRY and finally can tell try as hard as possible without
the OOM killer.
Xfs code already has an existing annotation for allocations which are
allowed to fail and we can trivially map them to the new gfp flag
because it will provide the semantic KM_MAYFAIL wants. Christoph didn't
consider the new flag really necessary but didn't respond to the OOM
killer aspect of the change so I have kept the patch. If this is still
seen as not really needed I can drop the patch.
kvmalloc will allow also !costly high order allocations to retry hard
before falling back to the vmalloc.
drm/i915 asked for the new semantic explicitly.
Memory migration code, especially for the memory hotplug, should back
off rather than invoking the OOM killer as well.
This patch (of 6):
Commit 3377e227af ("MIPS: Add 48-bit VA space (and 4-level page
tables) for 4K pages.") has added a new __GFP_REPEAT user but using this
flag doesn't really make any sense for order-0 request which is the case
here because PUD_ORDER is 0. __GFP_REPEAT has historically effect only
on allocation requests with order > PAGE_ALLOC_COSTLY_ORDER.
This doesn't introduce any functional change. This is a preparatory
patch for later work which renames the flag and redefines its semantic.
Link: http://lkml.kernel.org/r/20170623085345.11304-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Alex Belits <alex.belits@cavium.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: NeilBrown <neilb@suse.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
144 lines
3.2 KiB
C
144 lines
3.2 KiB
C
/*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (C) 1994 - 2001, 2003 by Ralf Baechle
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* Copyright (C) 1999, 2000, 2001 Silicon Graphics, Inc.
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*/
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#ifndef _ASM_PGALLOC_H
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#define _ASM_PGALLOC_H
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#include <linux/highmem.h>
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#include <linux/mm.h>
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#include <linux/sched.h>
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static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd,
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pte_t *pte)
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{
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set_pmd(pmd, __pmd((unsigned long)pte));
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}
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static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd,
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pgtable_t pte)
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{
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set_pmd(pmd, __pmd((unsigned long)page_address(pte)));
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}
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#define pmd_pgtable(pmd) pmd_page(pmd)
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/*
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* Initialize a new pmd table with invalid pointers.
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*/
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extern void pmd_init(unsigned long page, unsigned long pagetable);
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#ifndef __PAGETABLE_PMD_FOLDED
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static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
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{
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set_pud(pud, __pud((unsigned long)pmd));
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}
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#endif
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/*
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* Initialize a new pgd / pmd table with invalid pointers.
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*/
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extern void pgd_init(unsigned long page);
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extern pgd_t *pgd_alloc(struct mm_struct *mm);
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static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
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{
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free_pages((unsigned long)pgd, PGD_ORDER);
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}
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static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm,
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unsigned long address)
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{
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return (pte_t *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, PTE_ORDER);
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}
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static inline struct page *pte_alloc_one(struct mm_struct *mm,
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unsigned long address)
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{
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struct page *pte;
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pte = alloc_pages(GFP_KERNEL, PTE_ORDER);
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if (!pte)
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return NULL;
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clear_highpage(pte);
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if (!pgtable_page_ctor(pte)) {
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__free_page(pte);
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return NULL;
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}
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return pte;
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}
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static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
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{
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free_pages((unsigned long)pte, PTE_ORDER);
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}
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static inline void pte_free(struct mm_struct *mm, pgtable_t pte)
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{
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pgtable_page_dtor(pte);
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__free_pages(pte, PTE_ORDER);
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}
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#define __pte_free_tlb(tlb,pte,address) \
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do { \
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pgtable_page_dtor(pte); \
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tlb_remove_page((tlb), pte); \
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} while (0)
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#ifndef __PAGETABLE_PMD_FOLDED
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static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
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{
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pmd_t *pmd;
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pmd = (pmd_t *) __get_free_pages(GFP_KERNEL, PMD_ORDER);
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if (pmd)
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pmd_init((unsigned long)pmd, (unsigned long)invalid_pte_table);
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return pmd;
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}
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static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
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{
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free_pages((unsigned long)pmd, PMD_ORDER);
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}
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#define __pmd_free_tlb(tlb, x, addr) pmd_free((tlb)->mm, x)
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#endif
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#ifndef __PAGETABLE_PUD_FOLDED
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static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long address)
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{
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pud_t *pud;
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pud = (pud_t *) __get_free_pages(GFP_KERNEL, PUD_ORDER);
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if (pud)
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pud_init((unsigned long)pud, (unsigned long)invalid_pmd_table);
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return pud;
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}
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static inline void pud_free(struct mm_struct *mm, pud_t *pud)
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{
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free_pages((unsigned long)pud, PUD_ORDER);
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}
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static inline void pgd_populate(struct mm_struct *mm, pgd_t *pgd, pud_t *pud)
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{
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set_pgd(pgd, __pgd((unsigned long)pud));
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}
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#define __pud_free_tlb(tlb, x, addr) pud_free((tlb)->mm, x)
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#endif /* __PAGETABLE_PUD_FOLDED */
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#define check_pgt_cache() do { } while (0)
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extern void pagetable_init(void);
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#endif /* _ASM_PGALLOC_H */
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