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772dd03427
Introduce GFP bits enumeration to let compiler track the number of used bits (which depends on the config options) instead of hardcoding them. That simplifies __GFP_BITS_SHIFT calculation. Link: https://lkml.kernel.org/r/20240224015800.2569851-1-surenb@google.com Suggested-by: Petr Tesařík <petr@tesarici.cz> Signed-off-by: Suren Baghdasaryan <surenb@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: Petr Tesarik <petr@tesarici.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
375 lines
16 KiB
C
375 lines
16 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __LINUX_GFP_TYPES_H
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#define __LINUX_GFP_TYPES_H
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/* The typedef is in types.h but we want the documentation here */
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#if 0
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/**
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* typedef gfp_t - Memory allocation flags.
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*
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* GFP flags are commonly used throughout Linux to indicate how memory
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* should be allocated. The GFP acronym stands for get_free_pages(),
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* the underlying memory allocation function. Not every GFP flag is
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* supported by every function which may allocate memory. Most users
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* will want to use a plain ``GFP_KERNEL``.
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*/
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typedef unsigned int __bitwise gfp_t;
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#endif
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/*
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* In case of changes, please don't forget to update
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* include/trace/events/mmflags.h and tools/perf/builtin-kmem.c
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*/
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enum {
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___GFP_DMA_BIT,
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___GFP_HIGHMEM_BIT,
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___GFP_DMA32_BIT,
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___GFP_MOVABLE_BIT,
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___GFP_RECLAIMABLE_BIT,
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___GFP_HIGH_BIT,
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___GFP_IO_BIT,
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___GFP_FS_BIT,
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___GFP_ZERO_BIT,
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___GFP_UNUSED_BIT, /* 0x200u unused */
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___GFP_DIRECT_RECLAIM_BIT,
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___GFP_KSWAPD_RECLAIM_BIT,
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___GFP_WRITE_BIT,
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___GFP_NOWARN_BIT,
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___GFP_RETRY_MAYFAIL_BIT,
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___GFP_NOFAIL_BIT,
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___GFP_NORETRY_BIT,
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___GFP_MEMALLOC_BIT,
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___GFP_COMP_BIT,
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___GFP_NOMEMALLOC_BIT,
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___GFP_HARDWALL_BIT,
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___GFP_THISNODE_BIT,
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___GFP_ACCOUNT_BIT,
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___GFP_ZEROTAGS_BIT,
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#ifdef CONFIG_KASAN_HW_TAGS
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___GFP_SKIP_ZERO_BIT,
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___GFP_SKIP_KASAN_BIT,
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#endif
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#ifdef CONFIG_LOCKDEP
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___GFP_NOLOCKDEP_BIT,
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#endif
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___GFP_LAST_BIT
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};
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/* Plain integer GFP bitmasks. Do not use this directly. */
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#define ___GFP_DMA BIT(___GFP_DMA_BIT)
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#define ___GFP_HIGHMEM BIT(___GFP_HIGHMEM_BIT)
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#define ___GFP_DMA32 BIT(___GFP_DMA32_BIT)
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#define ___GFP_MOVABLE BIT(___GFP_MOVABLE_BIT)
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#define ___GFP_RECLAIMABLE BIT(___GFP_RECLAIMABLE_BIT)
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#define ___GFP_HIGH BIT(___GFP_HIGH_BIT)
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#define ___GFP_IO BIT(___GFP_IO_BIT)
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#define ___GFP_FS BIT(___GFP_FS_BIT)
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#define ___GFP_ZERO BIT(___GFP_ZERO_BIT)
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/* 0x200u unused */
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#define ___GFP_DIRECT_RECLAIM BIT(___GFP_DIRECT_RECLAIM_BIT)
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#define ___GFP_KSWAPD_RECLAIM BIT(___GFP_KSWAPD_RECLAIM_BIT)
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#define ___GFP_WRITE BIT(___GFP_WRITE_BIT)
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#define ___GFP_NOWARN BIT(___GFP_NOWARN_BIT)
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#define ___GFP_RETRY_MAYFAIL BIT(___GFP_RETRY_MAYFAIL_BIT)
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#define ___GFP_NOFAIL BIT(___GFP_NOFAIL_BIT)
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#define ___GFP_NORETRY BIT(___GFP_NORETRY_BIT)
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#define ___GFP_MEMALLOC BIT(___GFP_MEMALLOC_BIT)
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#define ___GFP_COMP BIT(___GFP_COMP_BIT)
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#define ___GFP_NOMEMALLOC BIT(___GFP_NOMEMALLOC_BIT)
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#define ___GFP_HARDWALL BIT(___GFP_HARDWALL_BIT)
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#define ___GFP_THISNODE BIT(___GFP_THISNODE_BIT)
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#define ___GFP_ACCOUNT BIT(___GFP_ACCOUNT_BIT)
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#define ___GFP_ZEROTAGS BIT(___GFP_ZEROTAGS_BIT)
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#ifdef CONFIG_KASAN_HW_TAGS
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#define ___GFP_SKIP_ZERO BIT(___GFP_SKIP_ZERO_BIT)
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#define ___GFP_SKIP_KASAN BIT(___GFP_SKIP_KASAN_BIT)
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#else
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#define ___GFP_SKIP_ZERO 0
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#define ___GFP_SKIP_KASAN 0
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#endif
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#ifdef CONFIG_LOCKDEP
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#define ___GFP_NOLOCKDEP BIT(___GFP_NOLOCKDEP_BIT)
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#else
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#define ___GFP_NOLOCKDEP 0
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#endif
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/*
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* Physical address zone modifiers (see linux/mmzone.h - low four bits)
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*
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* Do not put any conditional on these. If necessary modify the definitions
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* without the underscores and use them consistently. The definitions here may
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* be used in bit comparisons.
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*/
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#define __GFP_DMA ((__force gfp_t)___GFP_DMA)
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#define __GFP_HIGHMEM ((__force gfp_t)___GFP_HIGHMEM)
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#define __GFP_DMA32 ((__force gfp_t)___GFP_DMA32)
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#define __GFP_MOVABLE ((__force gfp_t)___GFP_MOVABLE) /* ZONE_MOVABLE allowed */
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#define GFP_ZONEMASK (__GFP_DMA|__GFP_HIGHMEM|__GFP_DMA32|__GFP_MOVABLE)
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/**
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* DOC: Page mobility and placement hints
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*
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* Page mobility and placement hints
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* ---------------------------------
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*
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* These flags provide hints about how mobile the page is. Pages with similar
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* mobility are placed within the same pageblocks to minimise problems due
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* to external fragmentation.
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*
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* %__GFP_MOVABLE (also a zone modifier) indicates that the page can be
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* moved by page migration during memory compaction or can be reclaimed.
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*
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* %__GFP_RECLAIMABLE is used for slab allocations that specify
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* SLAB_RECLAIM_ACCOUNT and whose pages can be freed via shrinkers.
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*
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* %__GFP_WRITE indicates the caller intends to dirty the page. Where possible,
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* these pages will be spread between local zones to avoid all the dirty
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* pages being in one zone (fair zone allocation policy).
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*
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* %__GFP_HARDWALL enforces the cpuset memory allocation policy.
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*
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* %__GFP_THISNODE forces the allocation to be satisfied from the requested
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* node with no fallbacks or placement policy enforcements.
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*
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* %__GFP_ACCOUNT causes the allocation to be accounted to kmemcg.
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*/
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#define __GFP_RECLAIMABLE ((__force gfp_t)___GFP_RECLAIMABLE)
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#define __GFP_WRITE ((__force gfp_t)___GFP_WRITE)
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#define __GFP_HARDWALL ((__force gfp_t)___GFP_HARDWALL)
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#define __GFP_THISNODE ((__force gfp_t)___GFP_THISNODE)
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#define __GFP_ACCOUNT ((__force gfp_t)___GFP_ACCOUNT)
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/**
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* DOC: Watermark modifiers
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*
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* Watermark modifiers -- controls access to emergency reserves
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* ------------------------------------------------------------
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*
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* %__GFP_HIGH indicates that the caller is high-priority and that granting
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* the request is necessary before the system can make forward progress.
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* For example creating an IO context to clean pages and requests
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* from atomic context.
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*
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* %__GFP_MEMALLOC allows access to all memory. This should only be used when
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* the caller guarantees the allocation will allow more memory to be freed
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* very shortly e.g. process exiting or swapping. Users either should
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* be the MM or co-ordinating closely with the VM (e.g. swap over NFS).
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* Users of this flag have to be extremely careful to not deplete the reserve
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* completely and implement a throttling mechanism which controls the
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* consumption of the reserve based on the amount of freed memory.
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* Usage of a pre-allocated pool (e.g. mempool) should be always considered
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* before using this flag.
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*
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* %__GFP_NOMEMALLOC is used to explicitly forbid access to emergency reserves.
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* This takes precedence over the %__GFP_MEMALLOC flag if both are set.
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*/
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#define __GFP_HIGH ((__force gfp_t)___GFP_HIGH)
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#define __GFP_MEMALLOC ((__force gfp_t)___GFP_MEMALLOC)
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#define __GFP_NOMEMALLOC ((__force gfp_t)___GFP_NOMEMALLOC)
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/**
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* DOC: Reclaim modifiers
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*
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* Reclaim modifiers
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* -----------------
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* Please note that all the following flags are only applicable to sleepable
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* allocations (e.g. %GFP_NOWAIT and %GFP_ATOMIC will ignore them).
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*
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* %__GFP_IO can start physical IO.
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*
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* %__GFP_FS can call down to the low-level FS. Clearing the flag avoids the
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* allocator recursing into the filesystem which might already be holding
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* locks.
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*
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* %__GFP_DIRECT_RECLAIM indicates that the caller may enter direct reclaim.
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* This flag can be cleared to avoid unnecessary delays when a fallback
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* option is available.
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*
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* %__GFP_KSWAPD_RECLAIM indicates that the caller wants to wake kswapd when
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* the low watermark is reached and have it reclaim pages until the high
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* watermark is reached. A caller may wish to clear this flag when fallback
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* options are available and the reclaim is likely to disrupt the system. The
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* canonical example is THP allocation where a fallback is cheap but
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* reclaim/compaction may cause indirect stalls.
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*
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* %__GFP_RECLAIM is shorthand to allow/forbid both direct and kswapd reclaim.
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*
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* The default allocator behavior depends on the request size. We have a concept
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* of so-called costly allocations (with order > %PAGE_ALLOC_COSTLY_ORDER).
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* !costly allocations are too essential to fail so they are implicitly
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* non-failing by default (with some exceptions like OOM victims might fail so
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* the caller still has to check for failures) while costly requests try to be
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* not disruptive and back off even without invoking the OOM killer.
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* The following three modifiers might be used to override some of these
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* implicit rules.
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*
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* %__GFP_NORETRY: The VM implementation will try only very lightweight
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* memory direct reclaim to get some memory under memory pressure (thus
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* it can sleep). It will avoid disruptive actions like OOM killer. The
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* caller must handle the failure which is quite likely to happen under
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* heavy memory pressure. The flag is suitable when failure can easily be
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* handled at small cost, such as reduced throughput.
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*
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* %__GFP_RETRY_MAYFAIL: The VM implementation will retry memory reclaim
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* procedures that have previously failed if there is some indication
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* that progress has been made elsewhere. It can wait for other
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* tasks to attempt high-level approaches to freeing memory such as
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* compaction (which removes fragmentation) and page-out.
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* There is still a definite limit to the number of retries, but it is
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* a larger limit than with %__GFP_NORETRY.
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* Allocations with this flag may fail, but only when there is
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* genuinely little unused memory. While these allocations do not
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* directly trigger the OOM killer, their failure indicates that
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* the system is likely to need to use the OOM killer soon. The
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* caller must handle failure, but can reasonably do so by failing
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* a higher-level request, or completing it only in a much less
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* efficient manner.
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* If the allocation does fail, and the caller is in a position to
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* free some non-essential memory, doing so could benefit the system
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* as a whole.
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*
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* %__GFP_NOFAIL: The VM implementation _must_ retry infinitely: the caller
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* cannot handle allocation failures. The allocation could block
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* indefinitely but will never return with failure. Testing for
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* failure is pointless.
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* New users should be evaluated carefully (and the flag should be
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* used only when there is no reasonable failure policy) but it is
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* definitely preferable to use the flag rather than opencode endless
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* loop around allocator.
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* Using this flag for costly allocations is _highly_ discouraged.
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*/
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#define __GFP_IO ((__force gfp_t)___GFP_IO)
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#define __GFP_FS ((__force gfp_t)___GFP_FS)
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#define __GFP_DIRECT_RECLAIM ((__force gfp_t)___GFP_DIRECT_RECLAIM) /* Caller can reclaim */
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#define __GFP_KSWAPD_RECLAIM ((__force gfp_t)___GFP_KSWAPD_RECLAIM) /* kswapd can wake */
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#define __GFP_RECLAIM ((__force gfp_t)(___GFP_DIRECT_RECLAIM|___GFP_KSWAPD_RECLAIM))
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#define __GFP_RETRY_MAYFAIL ((__force gfp_t)___GFP_RETRY_MAYFAIL)
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#define __GFP_NOFAIL ((__force gfp_t)___GFP_NOFAIL)
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#define __GFP_NORETRY ((__force gfp_t)___GFP_NORETRY)
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/**
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* DOC: Action modifiers
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*
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* Action modifiers
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* ----------------
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*
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* %__GFP_NOWARN suppresses allocation failure reports.
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*
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* %__GFP_COMP address compound page metadata.
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*
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* %__GFP_ZERO returns a zeroed page on success.
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*
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* %__GFP_ZEROTAGS zeroes memory tags at allocation time if the memory itself
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* is being zeroed (either via __GFP_ZERO or via init_on_alloc, provided that
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* __GFP_SKIP_ZERO is not set). This flag is intended for optimization: setting
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* memory tags at the same time as zeroing memory has minimal additional
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* performance impact.
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*
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* %__GFP_SKIP_KASAN makes KASAN skip unpoisoning on page allocation.
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* Used for userspace and vmalloc pages; the latter are unpoisoned by
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* kasan_unpoison_vmalloc instead. For userspace pages, results in
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* poisoning being skipped as well, see should_skip_kasan_poison for
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* details. Only effective in HW_TAGS mode.
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*/
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#define __GFP_NOWARN ((__force gfp_t)___GFP_NOWARN)
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#define __GFP_COMP ((__force gfp_t)___GFP_COMP)
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#define __GFP_ZERO ((__force gfp_t)___GFP_ZERO)
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#define __GFP_ZEROTAGS ((__force gfp_t)___GFP_ZEROTAGS)
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#define __GFP_SKIP_ZERO ((__force gfp_t)___GFP_SKIP_ZERO)
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#define __GFP_SKIP_KASAN ((__force gfp_t)___GFP_SKIP_KASAN)
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/* Disable lockdep for GFP context tracking */
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#define __GFP_NOLOCKDEP ((__force gfp_t)___GFP_NOLOCKDEP)
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/* Room for N __GFP_FOO bits */
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#define __GFP_BITS_SHIFT ___GFP_LAST_BIT
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#define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
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/**
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* DOC: Useful GFP flag combinations
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*
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* Useful GFP flag combinations
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* ----------------------------
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*
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* Useful GFP flag combinations that are commonly used. It is recommended
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* that subsystems start with one of these combinations and then set/clear
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* %__GFP_FOO flags as necessary.
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*
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* %GFP_ATOMIC users can not sleep and need the allocation to succeed. A lower
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* watermark is applied to allow access to "atomic reserves".
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* The current implementation doesn't support NMI and few other strict
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* non-preemptive contexts (e.g. raw_spin_lock). The same applies to %GFP_NOWAIT.
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*
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* %GFP_KERNEL is typical for kernel-internal allocations. The caller requires
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* %ZONE_NORMAL or a lower zone for direct access but can direct reclaim.
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*
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* %GFP_KERNEL_ACCOUNT is the same as GFP_KERNEL, except the allocation is
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* accounted to kmemcg.
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*
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* %GFP_NOWAIT is for kernel allocations that should not stall for direct
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* reclaim, start physical IO or use any filesystem callback. It is very
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* likely to fail to allocate memory, even for very small allocations.
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*
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* %GFP_NOIO will use direct reclaim to discard clean pages or slab pages
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* that do not require the starting of any physical IO.
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* Please try to avoid using this flag directly and instead use
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* memalloc_noio_{save,restore} to mark the whole scope which cannot
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* perform any IO with a short explanation why. All allocation requests
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* will inherit GFP_NOIO implicitly.
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*
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* %GFP_NOFS will use direct reclaim but will not use any filesystem interfaces.
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* Please try to avoid using this flag directly and instead use
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* memalloc_nofs_{save,restore} to mark the whole scope which cannot/shouldn't
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* recurse into the FS layer with a short explanation why. All allocation
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* requests will inherit GFP_NOFS implicitly.
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*
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* %GFP_USER is for userspace allocations that also need to be directly
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* accessibly by the kernel or hardware. It is typically used by hardware
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* for buffers that are mapped to userspace (e.g. graphics) that hardware
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* still must DMA to. cpuset limits are enforced for these allocations.
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*
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* %GFP_DMA exists for historical reasons and should be avoided where possible.
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* The flags indicates that the caller requires that the lowest zone be
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* used (%ZONE_DMA or 16M on x86-64). Ideally, this would be removed but
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* it would require careful auditing as some users really require it and
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* others use the flag to avoid lowmem reserves in %ZONE_DMA and treat the
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* lowest zone as a type of emergency reserve.
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*
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* %GFP_DMA32 is similar to %GFP_DMA except that the caller requires a 32-bit
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* address. Note that kmalloc(..., GFP_DMA32) does not return DMA32 memory
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* because the DMA32 kmalloc cache array is not implemented.
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* (Reason: there is no such user in kernel).
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*
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* %GFP_HIGHUSER is for userspace allocations that may be mapped to userspace,
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* do not need to be directly accessible by the kernel but that cannot
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* move once in use. An example may be a hardware allocation that maps
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* data directly into userspace but has no addressing limitations.
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*
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* %GFP_HIGHUSER_MOVABLE is for userspace allocations that the kernel does not
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* need direct access to but can use kmap() when access is required. They
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* are expected to be movable via page reclaim or page migration. Typically,
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* pages on the LRU would also be allocated with %GFP_HIGHUSER_MOVABLE.
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*
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* %GFP_TRANSHUGE and %GFP_TRANSHUGE_LIGHT are used for THP allocations. They
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* are compound allocations that will generally fail quickly if memory is not
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* available and will not wake kswapd/kcompactd on failure. The _LIGHT
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* version does not attempt reclaim/compaction at all and is by default used
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* in page fault path, while the non-light is used by khugepaged.
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*/
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#define GFP_ATOMIC (__GFP_HIGH|__GFP_KSWAPD_RECLAIM)
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#define GFP_KERNEL (__GFP_RECLAIM | __GFP_IO | __GFP_FS)
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#define GFP_KERNEL_ACCOUNT (GFP_KERNEL | __GFP_ACCOUNT)
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#define GFP_NOWAIT (__GFP_KSWAPD_RECLAIM | __GFP_NOWARN)
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#define GFP_NOIO (__GFP_RECLAIM)
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#define GFP_NOFS (__GFP_RECLAIM | __GFP_IO)
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#define GFP_USER (__GFP_RECLAIM | __GFP_IO | __GFP_FS | __GFP_HARDWALL)
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#define GFP_DMA __GFP_DMA
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#define GFP_DMA32 __GFP_DMA32
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#define GFP_HIGHUSER (GFP_USER | __GFP_HIGHMEM)
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#define GFP_HIGHUSER_MOVABLE (GFP_HIGHUSER | __GFP_MOVABLE | __GFP_SKIP_KASAN)
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#define GFP_TRANSHUGE_LIGHT ((GFP_HIGHUSER_MOVABLE | __GFP_COMP | \
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__GFP_NOMEMALLOC | __GFP_NOWARN) & ~__GFP_RECLAIM)
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#define GFP_TRANSHUGE (GFP_TRANSHUGE_LIGHT | __GFP_DIRECT_RECLAIM)
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#endif /* __LINUX_GFP_TYPES_H */
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