diff options
Diffstat (limited to 'include/linux/gfp.h')
| -rw-r--r-- | include/linux/gfp.h | 251 |
1 files changed, 171 insertions, 80 deletions
diff --git a/include/linux/gfp.h b/include/linux/gfp.h index 369227202ac2..6523109e136d 100644 --- a/include/linux/gfp.h +++ b/include/linux/gfp.h @@ -39,9 +39,7 @@ struct vm_area_struct; /* If the above are modified, __GFP_BITS_SHIFT may need updating */ /* - * GFP bitmasks.. - * - * Zone modifiers (see linux/mmzone.h - low three bits) + * 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 @@ -51,120 +49,211 @@ struct vm_area_struct; #define __GFP_HIGHMEM ((__force gfp_t)___GFP_HIGHMEM) #define __GFP_DMA32 ((__force gfp_t)___GFP_DMA32) #define __GFP_MOVABLE ((__force gfp_t)___GFP_MOVABLE) /* Page is movable */ +#define __GFP_MOVABLE ((__force gfp_t)___GFP_MOVABLE) /* ZONE_MOVABLE allowed */ #define GFP_ZONEMASK (__GFP_DMA|__GFP_HIGHMEM|__GFP_DMA32|__GFP_MOVABLE) + /* - * Action modifiers - doesn't change the zoning + * Page mobility and placement hints * - * __GFP_REPEAT: Try hard to allocate the memory, but the allocation attempt - * _might_ fail. This depends upon the particular VM implementation. + * 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_NOFAIL: The VM implementation _must_ retry infinitely: the caller - * cannot handle allocation failures. 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. + * __GFP_MOVABLE (also a zone modifier) indicates that the page can be + * moved by page migration during memory compaction or can be reclaimed. * - * __GFP_NORETRY: The VM implementation must not retry indefinitely and will - * return NULL when direct reclaim and memory compaction have failed to allow - * the allocation to succeed. The OOM killer is not called with the current - * implementation. + * __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_MOVABLE: Flag that this page will be movable by the page migration - * mechanism or reclaimed + * __GFP_HARDWALL enforces the cpuset memory allocation policy. + * + * __GFP_THISNODE forces the allocation to be satisified from the requested + * node with no fallbacks or placement policy enforcements. */ -#define __GFP_ATOMIC ((__force gfp_t)___GFP_ATOMIC) /* Caller cannot wait or reschedule */ -#define __GFP_HIGH ((__force gfp_t)___GFP_HIGH) /* Should access emergency pools? */ -#define __GFP_IO ((__force gfp_t)___GFP_IO) /* Can start physical IO? */ -#define __GFP_FS ((__force gfp_t)___GFP_FS) /* Can call down to low-level FS? */ -#define __GFP_COLD ((__force gfp_t)___GFP_COLD) /* Cache-cold page required */ -#define __GFP_NOWARN ((__force gfp_t)___GFP_NOWARN) /* Suppress page allocation failure warning */ -#define __GFP_REPEAT ((__force gfp_t)___GFP_REPEAT) /* See above */ -#define __GFP_NOFAIL ((__force gfp_t)___GFP_NOFAIL) /* See above */ -#define __GFP_NORETRY ((__force gfp_t)___GFP_NORETRY) /* See above */ -#define __GFP_MEMALLOC ((__force gfp_t)___GFP_MEMALLOC)/* Allow access to emergency reserves */ -#define __GFP_COMP ((__force gfp_t)___GFP_COMP) /* Add compound page metadata */ -#define __GFP_ZERO ((__force gfp_t)___GFP_ZERO) /* Return zeroed page on success */ -#define __GFP_NOMEMALLOC ((__force gfp_t)___GFP_NOMEMALLOC) /* Don't use emergency reserves. - * This takes precedence over the - * __GFP_MEMALLOC flag if both are - * set - */ -#define __GFP_HARDWALL ((__force gfp_t)___GFP_HARDWALL) /* Enforce hardwall cpuset memory allocs */ -#define __GFP_THISNODE ((__force gfp_t)___GFP_THISNODE)/* No fallback, no policies */ -#define __GFP_RECLAIMABLE ((__force gfp_t)___GFP_RECLAIMABLE) /* Page is reclaimable */ -#define __GFP_NOACCOUNT ((__force gfp_t)___GFP_NOACCOUNT) /* Don't account to kmemcg */ -#define __GFP_NOTRACK ((__force gfp_t)___GFP_NOTRACK) /* Don't track with kmemcheck */ - -#define __GFP_OTHER_NODE ((__force gfp_t)___GFP_OTHER_NODE) /* On behalf of other node */ -#define __GFP_WRITE ((__force gfp_t)___GFP_WRITE) /* Allocator intends to dirty page */ +#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) /* - * A caller that is willing to wait may enter direct reclaim and will - * wake kswapd to reclaim pages in the background until the high - * watermark is met. A caller may wish to clear __GFP_DIRECT_RECLAIM to - * avoid unnecessary delays when a fallback option is available but - * still allow kswapd to reclaim in the background. The kswapd flag - * can be cleared when the reclaiming of pages would cause unnecessary - * disruption. + * 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). + * + * __GFP_NOMEMALLOC is used to explicitly forbid access to emergency reserves. + * This takes precedence over the __GFP_MEMALLOC flag if both are set. + * + * __GFP_NOACCOUNT ignores the accounting for kmemcg limit enforcement. */ -#define __GFP_RECLAIM ((__force gfp_t)(___GFP_DIRECT_RECLAIM|___GFP_KSWAPD_RECLAIM)) +#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) +#define __GFP_NOACCOUNT ((__force gfp_t)___GFP_NOACCOUNT) + +/* + * Reclaim modifiers + * + * __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. + * + * __GFP_REPEAT: Try hard to allocate the memory, but the allocation attempt + * _might_ fail. This depends upon the particular VM implementation. + * + * __GFP_NOFAIL: The VM implementation _must_ retry infinitely: the caller + * cannot handle allocation failures. 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. + * + * __GFP_NORETRY: The VM implementation must not retry indefinitely and will + * return NULL when direct reclaim and memory compaction have failed to allow + * the allocation to succeed. The OOM killer is not called with the current + * implementation. + */ +#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_REPEAT ((__force gfp_t)___GFP_REPEAT) +#define __GFP_NOFAIL ((__force gfp_t)___GFP_NOFAIL) +#define __GFP_NORETRY ((__force gfp_t)___GFP_NORETRY) /* - * This may seem redundant, but it's a way of annotating false positives vs. - * allocations that simply cannot be supported (e.g. page tables). + * Action modifiers + * + * __GFP_COLD indicates that the caller does not expect to be used in the near + * future. Where possible, a cache-cold page will be returned. + * + * __GFP_NOWARN suppresses allocation failure reports. + * + * __GFP_COMP address compound page metadata. + * + * __GFP_ZERO returns a zeroed page on success. + * + * __GFP_NOTRACK avoids tracking with kmemcheck. + * + * __GFP_NOTRACK_FALSE_POSITIVE is an alias of __GFP_NOTRACK. It's a means of + * distinguishing in the source between false positives and allocations that + * cannot be supported (e.g. page tables). + * + * __GFP_OTHER_NODE is for allocations that are on a remote node but that + * should not be accounted for as a remote allocation in vmstat. A + * typical user would be khugepaged collapsing a huge page on a remote + * node. */ +#define __GFP_COLD ((__force gfp_t)___GFP_COLD) +#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_NOTRACK ((__force gfp_t)___GFP_NOTRACK) #define __GFP_NOTRACK_FALSE_POSITIVE (__GFP_NOTRACK) +#define __GFP_OTHER_NODE ((__force gfp_t)___GFP_OTHER_NODE) -#define __GFP_BITS_SHIFT 26 /* Room for N __GFP_FOO bits */ +/* Room for N __GFP_FOO bits */ +#define __GFP_BITS_SHIFT 26 #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1)) /* - * GFP_ATOMIC callers can not sleep, need the allocation to succeed. - * A lower watermark is applied to allow access to "atomic reserves" + * 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" + * + * 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_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. + * + * GFP_NOFS will use direct reclaim but will not use any filesystem interfaces. + * + * 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. + * + * 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 is used for THP allocations. They are compound allocations + * that will fail quickly if memory is not available and will not wake + * kswapd on failure. */ #define GFP_ATOMIC (__GFP_HIGH|__GFP_ATOMIC|__GFP_KSWAPD_RECLAIM) +#define GFP_KERNEL (__GFP_RECLAIM | __GFP_IO | __GFP_FS) #define GFP_NOWAIT (__GFP_KSWAPD_RECLAIM) #define GFP_NOIO (__GFP_RECLAIM) #define GFP_NOFS (__GFP_RECLAIM | __GFP_IO) -#define GFP_KERNEL (__GFP_RECLAIM | __GFP_IO | __GFP_FS) #define GFP_TEMPORARY (__GFP_RECLAIM | __GFP_IO | __GFP_FS | \ __GFP_RECLAIMABLE) #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) #define GFP_TRANSHUGE ((GFP_HIGHUSER_MOVABLE | __GFP_COMP | \ __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN) & \ ~__GFP_KSWAPD_RECLAIM) -/* This mask makes up all the page movable related flags */ +/* Convert GFP flags to their corresponding migrate type */ #define GFP_MOVABLE_MASK (__GFP_RECLAIMABLE|__GFP_MOVABLE) #define GFP_MOVABLE_SHIFT 3 -/* Control page allocator reclaim behavior */ -#define GFP_RECLAIM_MASK (__GFP_RECLAIM|__GFP_HIGH|__GFP_IO|__GFP_FS|\ - __GFP_NOWARN|__GFP_REPEAT|__GFP_NOFAIL|\ - __GFP_NORETRY|__GFP_MEMALLOC|__GFP_NOMEMALLOC) - -/* Control slab gfp mask during early boot */ -#define GFP_BOOT_MASK (__GFP_BITS_MASK & ~(__GFP_RECLAIM|__GFP_IO|__GFP_FS)) - -/* Control allocation constraints */ -#define GFP_CONSTRAINT_MASK (__GFP_HARDWALL|__GFP_THISNODE) - -/* Do not use these with a slab allocator */ -#define GFP_SLAB_BUG_MASK (__GFP_DMA32|__GFP_HIGHMEM|~__GFP_BITS_MASK) - -/* Flag - indicates that the buffer will be suitable for DMA. Ignored on some - platforms, used as appropriate on others */ - -#define GFP_DMA __GFP_DMA - -/* 4GB DMA on some platforms */ -#define GFP_DMA32 __GFP_DMA32 - -/* Convert GFP flags to their corresponding migrate type */ static inline int gfpflags_to_migratetype(const gfp_t gfp_flags) { VM_WARN_ON((gfp_flags & GFP_MOVABLE_MASK) == GFP_MOVABLE_MASK); @@ -177,6 +266,8 @@ static inline int gfpflags_to_migratetype(const gfp_t gfp_flags) /* Group based on mobility */ return (gfp_flags & GFP_MOVABLE_MASK) >> GFP_MOVABLE_SHIFT; } +#undef GFP_MOVABLE_MASK +#undef GFP_MOVABLE_SHIFT static inline bool gfpflags_allow_blocking(const gfp_t gfp_flags) { |