On 06/23/2017 10:53 AM, Michal Hocko wrote: ... > diff --git a/include/linux/gfp.h b/include/linux/gfp.h > index 4c6656f1fee7..6be1f836b69e 100644 > --- a/include/linux/gfp.h > +++ b/include/linux/gfp.h > @@ -25,7 +25,7 @@ struct vm_area_struct; > #define ___GFP_FS 0x80u > #define ___GFP_COLD 0x100u > #define ___GFP_NOWARN 0x200u > -#define ___GFP_REPEAT 0x400u > +#define ___GFP_RETRY_MAYFAIL 0x400u > #define ___GFP_NOFAIL 0x800u > #define ___GFP_NORETRY 0x1000u > #define ___GFP_MEMALLOC 0x2000u > @@ -136,26 +136,55 @@ struct vm_area_struct; > * > * __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. > + * 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 (with some exceptions like OOM victims might fail) by default 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_NORERY. Also, __GFP_NORETRY ^ (for grep purposes). -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
