| Message ID | 20230113111217.14134-6-mgorman@techsingularity.net (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Discard __GFP_ATOMIC | expand |
On Fri 13-01-23 11:12:16, Mel Gorman wrote: > GFP_ATOMIC allocations get flagged ALLOC_HARDER which is a vague > description. In preparation for the removal of GFP_ATOMIC redefine > __GFP_ATOMIC to simply mean non-blocking and renaming ALLOC_HARDER to > ALLOC_NON_BLOCK accordingly. __GFP_HIGH is required for access to reserves > but non-blocking is granted more access. For example, GFP_NOWAIT is > non-blocking but has no special access to reserves. A __GFP_NOFAIL > blocking allocation is granted access similar to __GFP_HIGH if the > only alternative is an OOM kill. > > Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Michal Hocko <mhocko@suse.com> Thanks! > --- > mm/internal.h | 7 +++++-- > mm/page_alloc.c | 44 ++++++++++++++++++++++++-------------------- > 2 files changed, 29 insertions(+), 22 deletions(-) > > diff --git a/mm/internal.h b/mm/internal.h > index 8706d46863df..23a37588073a 100644 > --- a/mm/internal.h > +++ b/mm/internal.h > @@ -735,7 +735,10 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone, > #define ALLOC_OOM ALLOC_NO_WATERMARKS > #endif > > -#define ALLOC_HARDER 0x10 /* try to alloc harder */ > +#define ALLOC_NON_BLOCK 0x10 /* Caller cannot block. Allow access > + * to 25% of the min watermark or > + * 62.5% if __GFP_HIGH is set. > + */ > #define ALLOC_MIN_RESERVE 0x20 /* __GFP_HIGH set. Allow access to 50% > * of the min watermark. > */ > @@ -750,7 +753,7 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone, > #define ALLOC_KSWAPD 0x800 /* allow waking of kswapd, __GFP_KSWAPD_RECLAIM set */ > > /* Flags that allow allocations below the min watermark. */ > -#define ALLOC_RESERVES (ALLOC_HARDER|ALLOC_MIN_RESERVE|ALLOC_HIGHATOMIC|ALLOC_OOM) > +#define ALLOC_RESERVES (ALLOC_NON_BLOCK|ALLOC_MIN_RESERVE|ALLOC_HIGHATOMIC|ALLOC_OOM) > > enum ttu_flags; > struct tlbflush_unmap_batch; > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 6f41b84a97ac..b9ae0ba0a2ab 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -3989,18 +3989,19 @@ bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark, > * __GFP_HIGH allows access to 50% of the min reserve as well > * as OOM. > */ > - if (alloc_flags & ALLOC_MIN_RESERVE) > + if (alloc_flags & ALLOC_MIN_RESERVE) { > min -= min / 2; > > - /* > - * Non-blocking allocations can access some of the reserve > - * with more access if also __GFP_HIGH. The reasoning is that > - * a non-blocking caller may incur a more severe penalty > - * if it cannot get memory quickly, particularly if it's > - * also __GFP_HIGH. > - */ > - if (alloc_flags & ALLOC_HARDER) > - min -= min / 4; > + /* > + * Non-blocking allocations (e.g. GFP_ATOMIC) can > + * access more reserves than just __GFP_HIGH. Other > + * non-blocking allocations requests such as GFP_NOWAIT > + * or (GFP_KERNEL & ~__GFP_DIRECT_RECLAIM) do not get > + * access to the min reserve. > + */ > + if (alloc_flags & ALLOC_NON_BLOCK) > + min -= min / 4; > + } > > /* > * OOM victims can try even harder than the normal reserve > @@ -4851,28 +4852,30 @@ gfp_to_alloc_flags(gfp_t gfp_mask, unsigned int order) > * The caller may dip into page reserves a bit more if the caller > * cannot run direct reclaim, or if the caller has realtime scheduling > * policy or is asking for __GFP_HIGH memory. GFP_ATOMIC requests will > - * set both ALLOC_HARDER (__GFP_ATOMIC) and ALLOC_MIN_RESERVE(__GFP_HIGH). > + * set both ALLOC_NON_BLOCK and ALLOC_MIN_RESERVE(__GFP_HIGH). > */ > alloc_flags |= (__force int) > (gfp_mask & (__GFP_HIGH | __GFP_KSWAPD_RECLAIM)); > > - if (gfp_mask & __GFP_ATOMIC) { > + if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) { > /* > * Not worth trying to allocate harder for __GFP_NOMEMALLOC even > * if it can't schedule. > */ > if (!(gfp_mask & __GFP_NOMEMALLOC)) { > - alloc_flags |= ALLOC_HARDER; > + alloc_flags |= ALLOC_NON_BLOCK; > > if (order > 0) > alloc_flags |= ALLOC_HIGHATOMIC; > } > > /* > - * Ignore cpuset mems for GFP_ATOMIC rather than fail, see the > - * comment for __cpuset_node_allowed(). > + * Ignore cpuset mems for non-blocking __GFP_HIGH (probably > + * GFP_ATOMIC) rather than fail, see the comment for > + * __cpuset_node_allowed(). > */ > - alloc_flags &= ~ALLOC_CPUSET; > + if (alloc_flags & ALLOC_MIN_RESERVE) > + alloc_flags &= ~ALLOC_CPUSET; > } else if (unlikely(rt_task(current)) && in_task()) > alloc_flags |= ALLOC_MIN_RESERVE; > > @@ -5303,12 +5306,13 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, > WARN_ON_ONCE_GFP(costly_order, gfp_mask); > > /* > - * Help non-failing allocations by giving them access to memory > - * reserves but do not use ALLOC_NO_WATERMARKS because this > + * Help non-failing allocations by giving some access to memory > + * reserves normally used for high priority non-blocking > + * allocations but do not use ALLOC_NO_WATERMARKS because this > * could deplete whole memory reserves which would just make > - * the situation worse > + * the situation worse. > */ > - page = __alloc_pages_cpuset_fallback(gfp_mask, order, ALLOC_HARDER, ac); > + page = __alloc_pages_cpuset_fallback(gfp_mask, order, ALLOC_MIN_RESERVE, ac); > if (page) > goto got_pg; > > -- > 2.35.3
On 1/13/23 12:12, Mel Gorman wrote: > GFP_ATOMIC allocations get flagged ALLOC_HARDER which is a vague > description. In preparation for the removal of GFP_ATOMIC redefine ^ __GFP_ATOMC > __GFP_ATOMIC to simply mean non-blocking and renaming ALLOC_HARDER to > ALLOC_NON_BLOCK accordingly. __GFP_HIGH is required for access to reserves > but non-blocking is granted more access. For example, GFP_NOWAIT is > non-blocking but has no special access to reserves. A __GFP_NOFAIL > blocking allocation is granted access similar to __GFP_HIGH if the > only alternative is an OOM kill. > > Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Well just for the lore record (too late for git) Acked-by: Vlastimil Babka <vbabka@suse.cz> Nit below: > --- > mm/internal.h | 7 +++++-- > mm/page_alloc.c | 44 ++++++++++++++++++++++++-------------------- > 2 files changed, 29 insertions(+), 22 deletions(-) > > diff --git a/mm/internal.h b/mm/internal.h > index 8706d46863df..23a37588073a 100644 > --- a/mm/internal.h > +++ b/mm/internal.h > @@ -735,7 +735,10 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone, > #define ALLOC_OOM ALLOC_NO_WATERMARKS > #endif > > -#define ALLOC_HARDER 0x10 /* try to alloc harder */ > +#define ALLOC_NON_BLOCK 0x10 /* Caller cannot block. Allow access > + * to 25% of the min watermark or > + * 62.5% if __GFP_HIGH is set. This is now (as of v3) inaccurate (the 25% part), right? > + */ > #define ALLOC_MIN_RESERVE 0x20 /* __GFP_HIGH set. Allow access to 50% > * of the min watermark. > */ > @@ -750,7 +753,7 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone, > #define ALLOC_KSWAPD 0x800 /* allow waking of kswapd, __GFP_KSWAPD_RECLAIM set */ > > /* Flags that allow allocations below the min watermark. */ > -#define ALLOC_RESERVES (ALLOC_HARDER|ALLOC_MIN_RESERVE|ALLOC_HIGHATOMIC|ALLOC_OOM) > +#define ALLOC_RESERVES (ALLOC_NON_BLOCK|ALLOC_MIN_RESERVE|ALLOC_HIGHATOMIC|ALLOC_OOM) > > enum ttu_flags; > struct tlbflush_unmap_batch; > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 6f41b84a97ac..b9ae0ba0a2ab 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -3989,18 +3989,19 @@ bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark, > * __GFP_HIGH allows access to 50% of the min reserve as well > * as OOM. > */ > - if (alloc_flags & ALLOC_MIN_RESERVE) > + if (alloc_flags & ALLOC_MIN_RESERVE) { > min -= min / 2; > > - /* > - * Non-blocking allocations can access some of the reserve > - * with more access if also __GFP_HIGH. The reasoning is that > - * a non-blocking caller may incur a more severe penalty > - * if it cannot get memory quickly, particularly if it's > - * also __GFP_HIGH. > - */ > - if (alloc_flags & ALLOC_HARDER) > - min -= min / 4; > + /* > + * Non-blocking allocations (e.g. GFP_ATOMIC) can > + * access more reserves than just __GFP_HIGH. Other > + * non-blocking allocations requests such as GFP_NOWAIT > + * or (GFP_KERNEL & ~__GFP_DIRECT_RECLAIM) do not get > + * access to the min reserve. > + */ > + if (alloc_flags & ALLOC_NON_BLOCK) > + min -= min / 4; > + } > > /* > * OOM victims can try even harder than the normal reserve > @@ -4851,28 +4852,30 @@ gfp_to_alloc_flags(gfp_t gfp_mask, unsigned int order) > * The caller may dip into page reserves a bit more if the caller > * cannot run direct reclaim, or if the caller has realtime scheduling > * policy or is asking for __GFP_HIGH memory. GFP_ATOMIC requests will > - * set both ALLOC_HARDER (__GFP_ATOMIC) and ALLOC_MIN_RESERVE(__GFP_HIGH). > + * set both ALLOC_NON_BLOCK and ALLOC_MIN_RESERVE(__GFP_HIGH). > */ > alloc_flags |= (__force int) > (gfp_mask & (__GFP_HIGH | __GFP_KSWAPD_RECLAIM)); > > - if (gfp_mask & __GFP_ATOMIC) { > + if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) { > /* > * Not worth trying to allocate harder for __GFP_NOMEMALLOC even > * if it can't schedule. > */ > if (!(gfp_mask & __GFP_NOMEMALLOC)) { > - alloc_flags |= ALLOC_HARDER; > + alloc_flags |= ALLOC_NON_BLOCK; > > if (order > 0) > alloc_flags |= ALLOC_HIGHATOMIC; > } > > /* > - * Ignore cpuset mems for GFP_ATOMIC rather than fail, see the > - * comment for __cpuset_node_allowed(). > + * Ignore cpuset mems for non-blocking __GFP_HIGH (probably > + * GFP_ATOMIC) rather than fail, see the comment for > + * __cpuset_node_allowed(). > */ > - alloc_flags &= ~ALLOC_CPUSET; > + if (alloc_flags & ALLOC_MIN_RESERVE) > + alloc_flags &= ~ALLOC_CPUSET; > } else if (unlikely(rt_task(current)) && in_task()) > alloc_flags |= ALLOC_MIN_RESERVE; > > @@ -5303,12 +5306,13 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, > WARN_ON_ONCE_GFP(costly_order, gfp_mask); > > /* > - * Help non-failing allocations by giving them access to memory > - * reserves but do not use ALLOC_NO_WATERMARKS because this > + * Help non-failing allocations by giving some access to memory > + * reserves normally used for high priority non-blocking > + * allocations but do not use ALLOC_NO_WATERMARKS because this > * could deplete whole memory reserves which would just make > - * the situation worse > + * the situation worse. > */ > - page = __alloc_pages_cpuset_fallback(gfp_mask, order, ALLOC_HARDER, ac); > + page = __alloc_pages_cpuset_fallback(gfp_mask, order, ALLOC_MIN_RESERVE, ac); > if (page) > goto got_pg; >
diff --git a/mm/internal.h b/mm/internal.h index 8706d46863df..23a37588073a 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -735,7 +735,10 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone, #define ALLOC_OOM ALLOC_NO_WATERMARKS #endif -#define ALLOC_HARDER 0x10 /* try to alloc harder */ +#define ALLOC_NON_BLOCK 0x10 /* Caller cannot block. Allow access + * to 25% of the min watermark or + * 62.5% if __GFP_HIGH is set. + */ #define ALLOC_MIN_RESERVE 0x20 /* __GFP_HIGH set. Allow access to 50% * of the min watermark. */ @@ -750,7 +753,7 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone, #define ALLOC_KSWAPD 0x800 /* allow waking of kswapd, __GFP_KSWAPD_RECLAIM set */ /* Flags that allow allocations below the min watermark. */ -#define ALLOC_RESERVES (ALLOC_HARDER|ALLOC_MIN_RESERVE|ALLOC_HIGHATOMIC|ALLOC_OOM) +#define ALLOC_RESERVES (ALLOC_NON_BLOCK|ALLOC_MIN_RESERVE|ALLOC_HIGHATOMIC|ALLOC_OOM) enum ttu_flags; struct tlbflush_unmap_batch; diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 6f41b84a97ac..b9ae0ba0a2ab 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3989,18 +3989,19 @@ bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark, * __GFP_HIGH allows access to 50% of the min reserve as well * as OOM. */ - if (alloc_flags & ALLOC_MIN_RESERVE) + if (alloc_flags & ALLOC_MIN_RESERVE) { min -= min / 2; - /* - * Non-blocking allocations can access some of the reserve - * with more access if also __GFP_HIGH. The reasoning is that - * a non-blocking caller may incur a more severe penalty - * if it cannot get memory quickly, particularly if it's - * also __GFP_HIGH. - */ - if (alloc_flags & ALLOC_HARDER) - min -= min / 4; + /* + * Non-blocking allocations (e.g. GFP_ATOMIC) can + * access more reserves than just __GFP_HIGH. Other + * non-blocking allocations requests such as GFP_NOWAIT + * or (GFP_KERNEL & ~__GFP_DIRECT_RECLAIM) do not get + * access to the min reserve. + */ + if (alloc_flags & ALLOC_NON_BLOCK) + min -= min / 4; + } /* * OOM victims can try even harder than the normal reserve @@ -4851,28 +4852,30 @@ gfp_to_alloc_flags(gfp_t gfp_mask, unsigned int order) * The caller may dip into page reserves a bit more if the caller * cannot run direct reclaim, or if the caller has realtime scheduling * policy or is asking for __GFP_HIGH memory. GFP_ATOMIC requests will - * set both ALLOC_HARDER (__GFP_ATOMIC) and ALLOC_MIN_RESERVE(__GFP_HIGH). + * set both ALLOC_NON_BLOCK and ALLOC_MIN_RESERVE(__GFP_HIGH). */ alloc_flags |= (__force int) (gfp_mask & (__GFP_HIGH | __GFP_KSWAPD_RECLAIM)); - if (gfp_mask & __GFP_ATOMIC) { + if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) { /* * Not worth trying to allocate harder for __GFP_NOMEMALLOC even * if it can't schedule. */ if (!(gfp_mask & __GFP_NOMEMALLOC)) { - alloc_flags |= ALLOC_HARDER; + alloc_flags |= ALLOC_NON_BLOCK; if (order > 0) alloc_flags |= ALLOC_HIGHATOMIC; } /* - * Ignore cpuset mems for GFP_ATOMIC rather than fail, see the - * comment for __cpuset_node_allowed(). + * Ignore cpuset mems for non-blocking __GFP_HIGH (probably + * GFP_ATOMIC) rather than fail, see the comment for + * __cpuset_node_allowed(). */ - alloc_flags &= ~ALLOC_CPUSET; + if (alloc_flags & ALLOC_MIN_RESERVE) + alloc_flags &= ~ALLOC_CPUSET; } else if (unlikely(rt_task(current)) && in_task()) alloc_flags |= ALLOC_MIN_RESERVE; @@ -5303,12 +5306,13 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, WARN_ON_ONCE_GFP(costly_order, gfp_mask); /* - * Help non-failing allocations by giving them access to memory - * reserves but do not use ALLOC_NO_WATERMARKS because this + * Help non-failing allocations by giving some access to memory + * reserves normally used for high priority non-blocking + * allocations but do not use ALLOC_NO_WATERMARKS because this * could deplete whole memory reserves which would just make - * the situation worse + * the situation worse. */ - page = __alloc_pages_cpuset_fallback(gfp_mask, order, ALLOC_HARDER, ac); + page = __alloc_pages_cpuset_fallback(gfp_mask, order, ALLOC_MIN_RESERVE, ac); if (page) goto got_pg;
GFP_ATOMIC allocations get flagged ALLOC_HARDER which is a vague description. In preparation for the removal of GFP_ATOMIC redefine __GFP_ATOMIC to simply mean non-blocking and renaming ALLOC_HARDER to ALLOC_NON_BLOCK accordingly. __GFP_HIGH is required for access to reserves but non-blocking is granted more access. For example, GFP_NOWAIT is non-blocking but has no special access to reserves. A __GFP_NOFAIL blocking allocation is granted access similar to __GFP_HIGH if the only alternative is an OOM kill. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> --- mm/internal.h | 7 +++++-- mm/page_alloc.c | 44 ++++++++++++++++++++++++-------------------- 2 files changed, 29 insertions(+), 22 deletions(-)