OSCL-LXR linux-6.0.1/​include/​linux/​gfp_types.h	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 /* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __LINUX_GFP_TYPES_H
 #define __LINUX_GFP_TYPES_H
 
 /* The typedef is in types.h but we want the documentation here */
 #if 0
 /**
  * typedef gfp_t - Memory allocation flags.
  *
  * GFP flags are commonly used throughout Linux to indicate how memory
  * should be allocated.  The GFP acronym stands for get_free_pages(),
  * the underlying memory allocation function.  Not every GFP flag is
  * supported by every function which may allocate memory.  Most users
  * will want to use a plain ``GFP_KERNEL``.
  */
 typedef unsigned int __bitwise gfp_t;
 #endif
 
 /*
  * In case of changes, please don't forget to update
  * include/trace/events/mmflags.h and tools/perf/builtin-kmem.c
  */
 
 /* Plain integer GFP bitmasks. Do not use this directly. */
 #define ___GFP_DMA      0x01u
 #define ___GFP_HIGHMEM      0x02u
 #define ___GFP_DMA32        0x04u
 #define ___GFP_MOVABLE      0x08u
 #define ___GFP_RECLAIMABLE  0x10u
 #define ___GFP_HIGH     0x20u
 #define ___GFP_IO       0x40u
 #define ___GFP_FS       0x80u
 #define ___GFP_ZERO     0x100u
 #define ___GFP_ATOMIC       0x200u
 #define ___GFP_DIRECT_RECLAIM   0x400u
 #define ___GFP_KSWAPD_RECLAIM   0x800u
 #define ___GFP_WRITE        0x1000u
 #define ___GFP_NOWARN       0x2000u
 #define ___GFP_RETRY_MAYFAIL    0x4000u
 #define ___GFP_NOFAIL       0x8000u
 #define ___GFP_NORETRY      0x10000u
 #define ___GFP_MEMALLOC     0x20000u
 #define ___GFP_COMP     0x40000u
 #define ___GFP_NOMEMALLOC   0x80000u
 #define ___GFP_HARDWALL     0x100000u
 #define ___GFP_THISNODE     0x200000u
 #define ___GFP_ACCOUNT      0x400000u
 #define ___GFP_ZEROTAGS     0x800000u
 #ifdef CONFIG_KASAN_HW_TAGS
 #define ___GFP_SKIP_ZERO        0x1000000u
 #define ___GFP_SKIP_KASAN_UNPOISON  0x2000000u
 #define ___GFP_SKIP_KASAN_POISON    0x4000000u
 #else
 #define ___GFP_SKIP_ZERO        0
 #define ___GFP_SKIP_KASAN_UNPOISON  0
 #define ___GFP_SKIP_KASAN_POISON    0
 #endif
 #ifdef CONFIG_LOCKDEP
 #define ___GFP_NOLOCKDEP    0x8000000u
 #else
 #define ___GFP_NOLOCKDEP    0
 #endif
 /* If the above are modified, __GFP_BITS_SHIFT may need updating */
 
 /*
  * Physical address zone modifiers (see linux/mmzone.h - low four bits)
  *
  * Do not put any conditional on these. If necessary modify the definitions
  * without the underscores and use them consistently. The definitions here may
  * be used in bit comparisons.
  */
 #define __GFP_DMA   ((__force gfp_t)___GFP_DMA)
 #define __GFP_HIGHMEM   ((__force gfp_t)___GFP_HIGHMEM)
 #define __GFP_DMA32 ((__force gfp_t)___GFP_DMA32)
 #define __GFP_MOVABLE   ((__force gfp_t)___GFP_MOVABLE)  /* ZONE_MOVABLE allowed */
 #define GFP_ZONEMASK    (__GFP_DMA|__GFP_HIGHMEM|__GFP_DMA32|__GFP_MOVABLE)
 
 /**
  * DOC: Page mobility and placement hints
  *
  * Page mobility and placement hints
  * ---------------------------------
  *
  * These flags provide hints about how mobile the page is. Pages with similar
  * mobility are placed within the same pageblocks to minimise problems due
  * to external fragmentation.
  *
  * %__GFP_MOVABLE (also a zone modifier) indicates that the page can be
  * moved by page migration during memory compaction or can be reclaimed.
  *
  * %__GFP_RECLAIMABLE is used for slab allocations that specify
  * SLAB_RECLAIM_ACCOUNT and whose pages can be freed via shrinkers.
  *
  * %__GFP_WRITE indicates the caller intends to dirty the page. Where possible,
  * these pages will be spread between local zones to avoid all the dirty
  * pages being in one zone (fair zone allocation policy).
  *
  * %__GFP_HARDWALL enforces the cpuset memory allocation policy.
  *
  * %__GFP_THISNODE forces the allocation to be satisfied from the requested
  * node with no fallbacks or placement policy enforcements.
  *
  * %__GFP_ACCOUNT causes the allocation to be accounted to kmemcg.
  */
 #define __GFP_RECLAIMABLE ((__force gfp_t)___GFP_RECLAIMABLE)
 #define __GFP_WRITE ((__force gfp_t)___GFP_WRITE)
 #define __GFP_HARDWALL   ((__force gfp_t)___GFP_HARDWALL)
 #define __GFP_THISNODE  ((__force gfp_t)___GFP_THISNODE)
 #define __GFP_ACCOUNT   ((__force gfp_t)___GFP_ACCOUNT)
 
 /**
  * DOC: Watermark modifiers
  *
  * Watermark modifiers -- controls access to emergency reserves
  * ------------------------------------------------------------
  *
  * %__GFP_HIGH indicates that the caller is high-priority and that granting
  * the request is necessary before the system can make forward progress.
  * For example, creating an IO context to clean pages.
  *
  * %__GFP_ATOMIC indicates that the caller cannot reclaim or sleep and is
  * high priority. Users are typically interrupt handlers. This may be
  * used in conjunction with %__GFP_HIGH
  *
  * %__GFP_MEMALLOC allows access to all memory. This should only be used when
  * the caller guarantees the allocation will allow more memory to be freed
  * very shortly e.g. process exiting or swapping. Users either should
  * be the MM or co-ordinating closely with the VM (e.g. swap over NFS).
  * Users of this flag have to be extremely careful to not deplete the reserve
  * completely and implement a throttling mechanism which controls the
  * consumption of the reserve based on the amount of freed memory.
  * Usage of a pre-allocated pool (e.g. mempool) should be always considered
  * before using this flag.
  *
  * %__GFP_NOMEMALLOC is used to explicitly forbid access to emergency reserves.
  * This takes precedence over the %__GFP_MEMALLOC flag if both are set.
  */
 #define __GFP_ATOMIC    ((__force gfp_t)___GFP_ATOMIC)
 #define __GFP_HIGH  ((__force gfp_t)___GFP_HIGH)
 #define __GFP_MEMALLOC  ((__force gfp_t)___GFP_MEMALLOC)
 #define __GFP_NOMEMALLOC ((__force gfp_t)___GFP_NOMEMALLOC)
 
 /**
  * DOC: Reclaim modifiers
  *
  * Reclaim modifiers
  * -----------------
  * Please note that all the following flags are only applicable to sleepable
  * allocations (e.g. %GFP_NOWAIT and %GFP_ATOMIC will ignore them).
  *
  * %__GFP_IO can start physical IO.
  *
  * %__GFP_FS can call down to the low-level FS. Clearing the flag avoids the
  * allocator recursing into the filesystem which might already be holding
  * locks.
  *
  * %__GFP_DIRECT_RECLAIM indicates that the caller may enter direct reclaim.
  * This flag can be cleared to avoid unnecessary delays when a fallback
  * option is available.
  *
  * %__GFP_KSWAPD_RECLAIM indicates that the caller wants to wake kswapd when
  * the low watermark is reached and have it reclaim pages until the high
  * watermark is reached. A caller may wish to clear this flag when fallback
  * options are available and the reclaim is likely to disrupt the system. The
  * canonical example is THP allocation where a fallback is cheap but
  * reclaim/compaction may cause indirect stalls.
  *
  * %__GFP_RECLAIM is shorthand to allow/forbid both direct and kswapd reclaim.
  *
  * The default allocator behavior depends on the request size. We have a concept
  * of so called costly allocations (with order > %PAGE_ALLOC_COSTLY_ORDER).
  * !costly allocations are too essential to fail so they are implicitly
  * non-failing by default (with some exceptions like OOM victims might fail so
  * the caller still has to check for failures) while costly requests try to be
  * not disruptive and back off even without invoking the OOM killer.
  * The following three modifiers might be used to override some of these
  * implicit rules
  *
  * %__GFP_NORETRY: The VM implementation will try only very lightweight
  * memory direct reclaim to get some memory under memory pressure (thus
  * it can sleep). It will avoid disruptive actions like OOM killer. The
  * caller must handle the failure which is quite likely to happen under
  * heavy memory pressure. The flag is suitable when failure can easily be
  * handled at small cost, such as reduced throughput
  *
  * %__GFP_RETRY_MAYFAIL: The VM implementation will retry memory reclaim
  * procedures that have previously failed if there is some indication
  * that progress has been made else where.  It can wait for other
  * tasks to attempt high level approaches to freeing memory such as
  * compaction (which removes fragmentation) and page-out.
  * There is still a definite limit to the number of retries, but it is
  * a larger limit than with %__GFP_NORETRY.
  * Allocations with this flag may fail, but only when there is
  * genuinely little unused memory. While these allocations do not
  * directly trigger the OOM killer, their failure indicates that
  * the system is likely to need to use the OOM killer soon.  The
  * caller must handle failure, but can reasonably do so by failing
  * a higher-level request, or completing it only in a much less
  * efficient manner.
  * If the allocation does fail, and the caller is in a position to
  * free some non-essential memory, doing so could benefit the system
  * as a whole.
  *
  * %__GFP_NOFAIL: The VM implementation _must_ retry infinitely: the caller
  * cannot handle allocation failures. The allocation could block
  * indefinitely but will never return with failure. Testing for
  * failure is pointless.
  * New users should be evaluated carefully (and the flag should be
  * used only when there is no reasonable failure policy) but it is
  * definitely preferable to use the flag rather than opencode endless
  * loop around allocator.
  * Using this flag for costly allocations is _highly_ discouraged.
  */
 #define __GFP_IO    ((__force gfp_t)___GFP_IO)
 #define __GFP_FS    ((__force gfp_t)___GFP_FS)
 #define __GFP_DIRECT_RECLAIM    ((__force gfp_t)___GFP_DIRECT_RECLAIM) /* Caller can reclaim */
 #define __GFP_KSWAPD_RECLAIM    ((__force gfp_t)___GFP_KSWAPD_RECLAIM) /* kswapd can wake */
 #define __GFP_RECLAIM ((__force gfp_t)(___GFP_DIRECT_RECLAIM|___GFP_KSWAPD_RECLAIM))
 #define __GFP_RETRY_MAYFAIL ((__force gfp_t)___GFP_RETRY_MAYFAIL)
 #define __GFP_NOFAIL    ((__force gfp_t)___GFP_NOFAIL)
 #define __GFP_NORETRY   ((__force gfp_t)___GFP_NORETRY)
 
 /**
  * DOC: Action modifiers
  *
  * Action modifiers
  * ----------------
  *
  * %__GFP_NOWARN suppresses allocation failure reports.
  *
  * %__GFP_COMP address compound page metadata.
  *
  * %__GFP_ZERO returns a zeroed page on success.
  *
  * %__GFP_ZEROTAGS zeroes memory tags at allocation time if the memory itself
  * is being zeroed (either via __GFP_ZERO or via init_on_alloc, provided that
  * __GFP_SKIP_ZERO is not set). This flag is intended for optimization: setting
  * memory tags at the same time as zeroing memory has minimal additional
  * performace impact.
  *
  * %__GFP_SKIP_KASAN_UNPOISON makes KASAN skip unpoisoning on page allocation.
  * Only effective in HW_TAGS mode.
  *
  * %__GFP_SKIP_KASAN_POISON makes KASAN skip poisoning on page deallocation.
  * Typically, used for userspace pages. Only effective in HW_TAGS mode.
  */
 #define __GFP_NOWARN    ((__force gfp_t)___GFP_NOWARN)
 #define __GFP_COMP  ((__force gfp_t)___GFP_COMP)
 #define __GFP_ZERO  ((__force gfp_t)___GFP_ZERO)
 #define __GFP_ZEROTAGS  ((__force gfp_t)___GFP_ZEROTAGS)
 #define __GFP_SKIP_ZERO ((__force gfp_t)___GFP_SKIP_ZERO)
 #define __GFP_SKIP_KASAN_UNPOISON ((__force gfp_t)___GFP_SKIP_KASAN_UNPOISON)
 #define __GFP_SKIP_KASAN_POISON   ((__force gfp_t)___GFP_SKIP_KASAN_POISON)
 
 /* Disable lockdep for GFP context tracking */
 #define __GFP_NOLOCKDEP ((__force gfp_t)___GFP_NOLOCKDEP)
 
 /* Room for N __GFP_FOO bits */
 #define __GFP_BITS_SHIFT (27 + IS_ENABLED(CONFIG_LOCKDEP))
 #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
 
 /**
  * DOC: Useful GFP flag combinations
  *
  * Useful GFP flag combinations
  * ----------------------------
  *
  * Useful GFP flag combinations that are commonly used. It is recommended
  * that subsystems start with one of these combinations and then set/clear
  * %__GFP_FOO flags as necessary.
  *
  * %GFP_ATOMIC users can not sleep and need the allocation to succeed. A lower
  * watermark is applied to allow access to "atomic reserves".
  * The current implementation doesn't support NMI and few other strict
  * non-preemptive contexts (e.g. raw_spin_lock). The same applies to %GFP_NOWAIT.
  *
  * %GFP_KERNEL is typical for kernel-internal allocations. The caller requires
  * %ZONE_NORMAL or a lower zone for direct access but can direct reclaim.
  *
  * %GFP_KERNEL_ACCOUNT is the same as GFP_KERNEL, except the allocation is
  * accounted to kmemcg.
  *
  * %GFP_NOWAIT is for kernel allocations that should not stall for direct
  * reclaim, start physical IO or use any filesystem callback.
  *
  * %GFP_NOIO will use direct reclaim to discard clean pages or slab pages
  * that do not require the starting of any physical IO.
  * Please try to avoid using this flag directly and instead use
  * memalloc_noio_{save,restore} to mark the whole scope which cannot
  * perform any IO with a short explanation why. All allocation requests
  * will inherit GFP_NOIO implicitly.
  *
  * %GFP_NOFS will use direct reclaim but will not use any filesystem interfaces.
  * Please try to avoid using this flag directly and instead use
  * memalloc_nofs_{save,restore} to mark the whole scope which cannot/shouldn't
  * recurse into the FS layer with a short explanation why. All allocation
  * requests will inherit GFP_NOFS implicitly.
  *
  * %GFP_USER is for userspace allocations that also need to be directly
  * accessibly by the kernel or hardware. It is typically used by hardware
  * for buffers that are mapped to userspace (e.g. graphics) that hardware
  * still must DMA to. cpuset limits are enforced for these allocations.
  *
  * %GFP_DMA exists for historical reasons and should be avoided where possible.
  * The flags indicates that the caller requires that the lowest zone be
  * used (%ZONE_DMA or 16M on x86-64). Ideally, this would be removed but
  * it would require careful auditing as some users really require it and
  * others use the flag to avoid lowmem reserves in %ZONE_DMA and treat the
  * lowest zone as a type of emergency reserve.
  *
  * %GFP_DMA32 is similar to %GFP_DMA except that the caller requires a 32-bit
  * address. Note that kmalloc(..., GFP_DMA32) does not return DMA32 memory
  * because the DMA32 kmalloc cache array is not implemented.
  * (Reason: there is no such user in kernel).
  *
  * %GFP_HIGHUSER is for userspace allocations that may be mapped to userspace,
  * do not need to be directly accessible by the kernel but that cannot
  * move once in use. An example may be a hardware allocation that maps
  * data directly into userspace but has no addressing limitations.
  *
  * %GFP_HIGHUSER_MOVABLE is for userspace allocations that the kernel does not
  * need direct access to but can use kmap() when access is required. They
  * are expected to be movable via page reclaim or page migration. Typically,
  * pages on the LRU would also be allocated with %GFP_HIGHUSER_MOVABLE.
  *
  * %GFP_TRANSHUGE and %GFP_TRANSHUGE_LIGHT are used for THP allocations. They
  * are compound allocations that will generally fail quickly if memory is not
  * available and will not wake kswapd/kcompactd on failure. The _LIGHT
  * version does not attempt reclaim/compaction at all and is by default used
  * in page fault path, while the non-light is used by khugepaged.
  */
 #define GFP_ATOMIC  (__GFP_HIGH|__GFP_ATOMIC|__GFP_KSWAPD_RECLAIM)
 #define GFP_KERNEL  (__GFP_RECLAIM | __GFP_IO | __GFP_FS)
 #define GFP_KERNEL_ACCOUNT (GFP_KERNEL | __GFP_ACCOUNT)
 #define GFP_NOWAIT  (__GFP_KSWAPD_RECLAIM)
 #define GFP_NOIO    (__GFP_RECLAIM)
 #define GFP_NOFS    (__GFP_RECLAIM | __GFP_IO)
 #define GFP_USER    (__GFP_RECLAIM | __GFP_IO | __GFP_FS | __GFP_HARDWALL)
 #define GFP_DMA     __GFP_DMA
 #define GFP_DMA32   __GFP_DMA32
 #define GFP_HIGHUSER    (GFP_USER | __GFP_HIGHMEM)
 #define GFP_HIGHUSER_MOVABLE    (GFP_HIGHUSER | __GFP_MOVABLE | \
              __GFP_SKIP_KASAN_POISON | __GFP_SKIP_KASAN_UNPOISON)
 #define GFP_TRANSHUGE_LIGHT ((GFP_HIGHUSER_MOVABLE | __GFP_COMP | \
              __GFP_NOMEMALLOC | __GFP_NOWARN) & ~__GFP_RECLAIM)
 #define GFP_TRANSHUGE   (GFP_TRANSHUGE_LIGHT | __GFP_DIRECT_RECLAIM)
 
 #endif /* __LINUX_GFP_TYPES_H */

This page was automatically generated by the 2.1.0 LXR engine. The LXR team