| Message ID | 20240822083842.3167137-1-hezhongkun.hzk@bytedance.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [V1] mm:page_alloc: fix the NULL ac->nodemask in __alloc_pages_slowpath() | expand |
On Thu 22-08-24 16:38:42, Zhongkun He wrote: > I found a problem in my test machine that should_reclaim_retry() do > not get the right node if i set the cpuset.mems. > The should_reclaim_retry() and try_to_compact_pages() are iterating > nodes which are not allowed by cpusets and that makes the retry loop > happening more than unnecessary. I would update the problem description because from the above it is not really clear what the actual problem is. should_reclaim_retry is not ALLOC_CPUSET aware and that means that it considers reclaimability of NUMA nodes which are outside of the cpuset. If other nodes have a lot of reclaimable memory then should_reclaim_retry would instruct page allocator to retry even though there is no memory reclaimable on the cpuset nodemask. This is not really a huge problem because the number of retries without any reclaim progress is bound but it could be certainly improved. This is a cold path so this shouldn't really have a measurable impact on performance on most workloads. > > 1.Test step and the machines. > ------------ > root@vm:/sys/fs/cgroup/test# numactl -H | grep size > node 0 size: 9477 MB > node 1 size: 10079 MB > node 2 size: 10079 MB > node 3 size: 10078 MB > > root@vm:/sys/fs/cgroup/test# cat cpuset.mems > 2 > > root@vm:/sys/fs/cgroup/test# stress --vm 1 --vm-bytes 12g --vm-keep > stress: info: [33430] dispatching hogs: 0 cpu, 0 io, 1 vm, 0 hdd > stress: FAIL: [33430] (425) <-- worker 33431 got signal 9 > stress: WARN: [33430] (427) now reaping child worker processes > stress: FAIL: [33430] (461) failed run completed in 2s > > 2. reclaim_retry_zone info: > > We can only alloc pages from node=2, but the reclaim_retry_zone is > node=0 and return true. > > root@vm:/sys/kernel/debug/tracing# cat trace > stress-33431 [001] ..... 13223.617311: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=1 wmark_check=1 > stress-33431 [001] ..... 13223.617682: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=2 wmark_check=1 > stress-33431 [001] ..... 13223.618103: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=3 wmark_check=1 > stress-33431 [001] ..... 13223.618454: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=4 wmark_check=1 > stress-33431 [001] ..... 13223.618770: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=5 wmark_check=1 > stress-33431 [001] ..... 13223.619150: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=6 wmark_check=1 > stress-33431 [001] ..... 13223.619510: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=7 wmark_check=1 > stress-33431 [001] ..... 13223.619850: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=8 wmark_check=1 > stress-33431 [001] ..... 13223.620171: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=9 wmark_check=1 > stress-33431 [001] ..... 13223.620533: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=10 wmark_check=1 > stress-33431 [001] ..... 13223.620894: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=11 wmark_check=1 > stress-33431 [001] ..... 13223.621224: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=12 wmark_check=1 > stress-33431 [001] ..... 13223.621551: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=13 wmark_check=1 > stress-33431 [001] ..... 13223.621847: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=14 wmark_check=1 > stress-33431 [001] ..... 13223.622200: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=15 wmark_check=1 > stress-33431 [001] ..... 13223.622580: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=16 wmark_check=1 > You can drop the following > 3. Root cause: > Nodemask usually comes from mempolicy in policy_nodemask(), which > is always NULL unless the memory policy is bind or prefer_many. > > nodemask = NULL > __alloc_pages_noprof() > prepare_alloc_pages > ac->nodemask = &cpuset_current_mems_allowed; > > get_page_from_freelist() > > ac.nodemask = nodemask; /*set NULL*/ > > __alloc_pages_slowpath() { > f (!(alloc_flags & ALLOC_CPUSET) || reserve_flags) { > ac->nodemask = NULL; > ac->preferred_zoneref = first_zones_zonelist(ac->zonelist, > ac->highest_zoneidx, ac->nodemask); > > /* so ac.nodemask = NULL */ > } > > According to the function flow above, we do not have the memory limit to > follow cpuset.mems, so we need to add it. > > Test result: > Try 3 times with different cpuset.mems and alloc large memorys than that numa size. > echo 1 > cpuset.mems > stress --vm 1 --vm-bytes 12g --vm-hang 0 > --------------- > echo 2 > cpuset.mems > stress --vm 1 --vm-bytes 12g --vm-hang 0 > --------------- > echo 3 > cpuset.mems > stress --vm 1 --vm-bytes 12g --vm-hang 0 > > The retry trace look like: > stress-2139 [003] ..... 666.934104: reclaim_retry_zone: node=1 zone=Normal order=0 reclaimable=7 available=7355 min_wmark=8598 no_progress_loops=1 wmark_check=0 > stress-2204 [010] ..... 695.447393: reclaim_retry_zone: node=2 zone=Normal order=0 reclaimable=2 available=6916 min_wmark=8598 no_progress_loops=1 wmark_check=0 > stress-2271 [008] ..... 725.683058: reclaim_retry_zone: node=3 zone=Normal order=0 reclaimable=17 available=8079 min_wmark=8597 no_progress_loops=1 wmark_check=0 > And only keep this > With this patch, we can check the right node and get less retry in __alloc_pages_slowpath() > because there is nothing to do. > > V1: > Do the same with the page allocator using __cpuset_zone_allowed(). > > Suggested-by: Michal Hocko <mhocko@suse.com> > Signed-off-by: Zhongkun He <hezhongkun.hzk@bytedance.com> With those changes you can add Acked-by: Michal Hocko <mhocko@suse.com> Thanks! > --- > mm/compaction.c | 6 ++++++ > mm/page_alloc.c | 5 +++++ > 2 files changed, 11 insertions(+) > > diff --git a/mm/compaction.c b/mm/compaction.c > index d1041fbce679..a2b16b08cbbf 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -23,6 +23,7 @@ > #include <linux/freezer.h> > #include <linux/page_owner.h> > #include <linux/psi.h> > +#include <linux/cpuset.h> > #include "internal.h" > > #ifdef CONFIG_COMPACTION > @@ -2822,6 +2823,11 @@ enum compact_result try_to_compact_pages(gfp_t gfp_mask, unsigned int order, > ac->highest_zoneidx, ac->nodemask) { > enum compact_result status; > > + if (cpusets_enabled() && > + (alloc_flags & ALLOC_CPUSET) && > + !__cpuset_zone_allowed(zone, gfp_mask)) > + continue; > + > if (prio > MIN_COMPACT_PRIORITY > && compaction_deferred(zone, order)) { > rc = max_t(enum compact_result, COMPACT_DEFERRED, rc); > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 29608ca294cf..8a67d760b71a 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -4128,6 +4128,11 @@ should_reclaim_retry(gfp_t gfp_mask, unsigned order, > unsigned long min_wmark = min_wmark_pages(zone); > bool wmark; > > + if (cpusets_enabled() && > + (alloc_flags & ALLOC_CPUSET) && > + !__cpuset_zone_allowed(zone, gfp_mask)) > + continue; > + > available = reclaimable = zone_reclaimable_pages(zone); > available += zone_page_state_snapshot(zone, NR_FREE_PAGES); > > -- > 2.20.1
On Thu, Aug 22, 2024 at 5:01 PM Michal Hocko <mhocko@suse.com> wrote: > > On Thu 22-08-24 16:38:42, Zhongkun He wrote: > > I found a problem in my test machine that should_reclaim_retry() do > > not get the right node if i set the cpuset.mems. > > The should_reclaim_retry() and try_to_compact_pages() are iterating > > nodes which are not allowed by cpusets and that makes the retry loop > > happening more than unnecessary. > > I would update the problem description because from the above it is not > really clear what the actual problem is. > > should_reclaim_retry is not ALLOC_CPUSET aware and that means that it > considers reclaimability of NUMA nodes which are outside of the cpuset. > If other nodes have a lot of reclaimable memory then should_reclaim_retry > would instruct page allocator to retry even though there is no memory > reclaimable on the cpuset nodemask. This is not really a huge problem > because the number of retries without any reclaim progress is bound but > it could be certainly improved. This is a cold path so this shouldn't > really have a measurable impact on performance on most workloads. > Thanks for your description about this case. > > > > 1.Test step and the machines. > > ------------ > > root@vm:/sys/fs/cgroup/test# numactl -H | grep size > > node 0 size: 9477 MB > > node 1 size: 10079 MB > > node 2 size: 10079 MB > > node 3 size: 10078 MB > > > > root@vm:/sys/fs/cgroup/test# cat cpuset.mems > > 2 > > > > root@vm:/sys/fs/cgroup/test# stress --vm 1 --vm-bytes 12g --vm-keep > > stress: info: [33430] dispatching hogs: 0 cpu, 0 io, 1 vm, 0 hdd > > stress: FAIL: [33430] (425) <-- worker 33431 got signal 9 > > stress: WARN: [33430] (427) now reaping child worker processes > > stress: FAIL: [33430] (461) failed run completed in 2s > > > > 2. reclaim_retry_zone info: > > > > We can only alloc pages from node=2, but the reclaim_retry_zone is > > node=0 and return true. > > > > root@vm:/sys/kernel/debug/tracing# cat trace > > stress-33431 [001] ..... 13223.617311: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=1 wmark_check=1 > > stress-33431 [001] ..... 13223.617682: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=2 wmark_check=1 > > stress-33431 [001] ..... 13223.618103: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=3 wmark_check=1 > > stress-33431 [001] ..... 13223.618454: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=4 wmark_check=1 > > stress-33431 [001] ..... 13223.618770: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=5 wmark_check=1 > > stress-33431 [001] ..... 13223.619150: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=6 wmark_check=1 > > stress-33431 [001] ..... 13223.619510: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=7 wmark_check=1 > > stress-33431 [001] ..... 13223.619850: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=8 wmark_check=1 > > stress-33431 [001] ..... 13223.620171: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=9 wmark_check=1 > > stress-33431 [001] ..... 13223.620533: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=10 wmark_check=1 > > stress-33431 [001] ..... 13223.620894: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=11 wmark_check=1 > > stress-33431 [001] ..... 13223.621224: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=12 wmark_check=1 > > stress-33431 [001] ..... 13223.621551: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=13 wmark_check=1 > > stress-33431 [001] ..... 13223.621847: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=14 wmark_check=1 > > stress-33431 [001] ..... 13223.622200: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=15 wmark_check=1 > > stress-33431 [001] ..... 13223.622580: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=16 wmark_check=1 > > > > You can drop the following > OK. > > 3. Root cause: > > Nodemask usually comes from mempolicy in policy_nodemask(), which > > is always NULL unless the memory policy is bind or prefer_many. > > > > nodemask = NULL > > __alloc_pages_noprof() > > prepare_alloc_pages > > ac->nodemask = &cpuset_current_mems_allowed; > > > > get_page_from_freelist() > > > > ac.nodemask = nodemask; /*set NULL*/ > > > > __alloc_pages_slowpath() { > > f (!(alloc_flags & ALLOC_CPUSET) || reserve_flags) { > > ac->nodemask = NULL; > > ac->preferred_zoneref = first_zones_zonelist(ac->zonelist, > > ac->highest_zoneidx, ac->nodemask); > > > > /* so ac.nodemask = NULL */ > > } > > > > According to the function flow above, we do not have the memory limit to > > follow cpuset.mems, so we need to add it. > > > > Test result: > > Try 3 times with different cpuset.mems and alloc large memorys than that numa size. > > echo 1 > cpuset.mems > > stress --vm 1 --vm-bytes 12g --vm-hang 0 > > --------------- > > echo 2 > cpuset.mems > > stress --vm 1 --vm-bytes 12g --vm-hang 0 > > --------------- > > echo 3 > cpuset.mems > > stress --vm 1 --vm-bytes 12g --vm-hang 0 > > > > The retry trace look like: > > stress-2139 [003] ..... 666.934104: reclaim_retry_zone: node=1 zone=Normal order=0 reclaimable=7 available=7355 min_wmark=8598 no_progress_loops=1 wmark_check=0 > > stress-2204 [010] ..... 695.447393: reclaim_retry_zone: node=2 zone=Normal order=0 reclaimable=2 available=6916 min_wmark=8598 no_progress_loops=1 wmark_check=0 > > stress-2271 [008] ..... 725.683058: reclaim_retry_zone: node=3 zone=Normal order=0 reclaimable=17 available=8079 min_wmark=8597 no_progress_loops=1 wmark_check=0 > > > > And only keep this > OK. > > With this patch, we can check the right node and get less retry in __alloc_pages_slowpath() > > because there is nothing to do. > > > > V1: > > Do the same with the page allocator using __cpuset_zone_allowed(). > > > > Suggested-by: Michal Hocko <mhocko@suse.com> > > Signed-off-by: Zhongkun He <hezhongkun.hzk@bytedance.com> > > With those changes you can add > Acked-by: Michal Hocko <mhocko@suse.com> > Thanks! > > > --- > > mm/compaction.c | 6 ++++++ > > mm/page_alloc.c | 5 +++++ > > 2 files changed, 11 insertions(+) > > > > diff --git a/mm/compaction.c b/mm/compaction.c > > index d1041fbce679..a2b16b08cbbf 100644 > > --- a/mm/compaction.c > > +++ b/mm/compaction.c > > @@ -23,6 +23,7 @@ > > #include <linux/freezer.h> > > #include <linux/page_owner.h> > > #include <linux/psi.h> > > +#include <linux/cpuset.h> > > #include "internal.h" > > > > #ifdef CONFIG_COMPACTION > > @@ -2822,6 +2823,11 @@ enum compact_result try_to_compact_pages(gfp_t gfp_mask, unsigned int order, > > ac->highest_zoneidx, ac->nodemask) { > > enum compact_result status; > > > > + if (cpusets_enabled() && > > + (alloc_flags & ALLOC_CPUSET) && > > + !__cpuset_zone_allowed(zone, gfp_mask)) > > + continue; > > + > > if (prio > MIN_COMPACT_PRIORITY > > && compaction_deferred(zone, order)) { > > rc = max_t(enum compact_result, COMPACT_DEFERRED, rc); > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index 29608ca294cf..8a67d760b71a 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -4128,6 +4128,11 @@ should_reclaim_retry(gfp_t gfp_mask, unsigned order, > > unsigned long min_wmark = min_wmark_pages(zone); > > bool wmark; > > > > + if (cpusets_enabled() && > > + (alloc_flags & ALLOC_CPUSET) && > > + !__cpuset_zone_allowed(zone, gfp_mask)) > > + continue; > > + > > available = reclaimable = zone_reclaimable_pages(zone); > > available += zone_page_state_snapshot(zone, NR_FREE_PAGES); > > > > -- > > 2.20.1 > > -- > Michal Hocko > SUSE Labs
diff --git a/mm/compaction.c b/mm/compaction.c index d1041fbce679..a2b16b08cbbf 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -23,6 +23,7 @@ #include <linux/freezer.h> #include <linux/page_owner.h> #include <linux/psi.h> +#include <linux/cpuset.h> #include "internal.h" #ifdef CONFIG_COMPACTION @@ -2822,6 +2823,11 @@ enum compact_result try_to_compact_pages(gfp_t gfp_mask, unsigned int order, ac->highest_zoneidx, ac->nodemask) { enum compact_result status; + if (cpusets_enabled() && + (alloc_flags & ALLOC_CPUSET) && + !__cpuset_zone_allowed(zone, gfp_mask)) + continue; + if (prio > MIN_COMPACT_PRIORITY && compaction_deferred(zone, order)) { rc = max_t(enum compact_result, COMPACT_DEFERRED, rc); diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 29608ca294cf..8a67d760b71a 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -4128,6 +4128,11 @@ should_reclaim_retry(gfp_t gfp_mask, unsigned order, unsigned long min_wmark = min_wmark_pages(zone); bool wmark; + if (cpusets_enabled() && + (alloc_flags & ALLOC_CPUSET) && + !__cpuset_zone_allowed(zone, gfp_mask)) + continue; + available = reclaimable = zone_reclaimable_pages(zone); available += zone_page_state_snapshot(zone, NR_FREE_PAGES);
I found a problem in my test machine that should_reclaim_retry() do not get the right node if i set the cpuset.mems. The should_reclaim_retry() and try_to_compact_pages() are iterating nodes which are not allowed by cpusets and that makes the retry loop happening more than unnecessary. 1.Test step and the machines. ------------ root@vm:/sys/fs/cgroup/test# numactl -H | grep size node 0 size: 9477 MB node 1 size: 10079 MB node 2 size: 10079 MB node 3 size: 10078 MB root@vm:/sys/fs/cgroup/test# cat cpuset.mems 2 root@vm:/sys/fs/cgroup/test# stress --vm 1 --vm-bytes 12g --vm-keep stress: info: [33430] dispatching hogs: 0 cpu, 0 io, 1 vm, 0 hdd stress: FAIL: [33430] (425) <-- worker 33431 got signal 9 stress: WARN: [33430] (427) now reaping child worker processes stress: FAIL: [33430] (461) failed run completed in 2s 2. reclaim_retry_zone info: We can only alloc pages from node=2, but the reclaim_retry_zone is node=0 and return true. root@vm:/sys/kernel/debug/tracing# cat trace stress-33431 [001] ..... 13223.617311: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=1 wmark_check=1 stress-33431 [001] ..... 13223.617682: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=2 wmark_check=1 stress-33431 [001] ..... 13223.618103: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=3 wmark_check=1 stress-33431 [001] ..... 13223.618454: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=4 wmark_check=1 stress-33431 [001] ..... 13223.618770: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=5 wmark_check=1 stress-33431 [001] ..... 13223.619150: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=6 wmark_check=1 stress-33431 [001] ..... 13223.619510: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=7 wmark_check=1 stress-33431 [001] ..... 13223.619850: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=8 wmark_check=1 stress-33431 [001] ..... 13223.620171: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=9 wmark_check=1 stress-33431 [001] ..... 13223.620533: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=10 wmark_check=1 stress-33431 [001] ..... 13223.620894: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=11 wmark_check=1 stress-33431 [001] ..... 13223.621224: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=12 wmark_check=1 stress-33431 [001] ..... 13223.621551: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=13 wmark_check=1 stress-33431 [001] ..... 13223.621847: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=14 wmark_check=1 stress-33431 [001] ..... 13223.622200: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=15 wmark_check=1 stress-33431 [001] ..... 13223.622580: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=16 wmark_check=1 3. Root cause: Nodemask usually comes from mempolicy in policy_nodemask(), which is always NULL unless the memory policy is bind or prefer_many. nodemask = NULL __alloc_pages_noprof() prepare_alloc_pages ac->nodemask = &cpuset_current_mems_allowed; get_page_from_freelist() ac.nodemask = nodemask; /*set NULL*/ __alloc_pages_slowpath() { f (!(alloc_flags & ALLOC_CPUSET) || reserve_flags) { ac->nodemask = NULL; ac->preferred_zoneref = first_zones_zonelist(ac->zonelist, ac->highest_zoneidx, ac->nodemask); /* so ac.nodemask = NULL */ } According to the function flow above, we do not have the memory limit to follow cpuset.mems, so we need to add it. Test result: Try 3 times with different cpuset.mems and alloc large memorys than that numa size. echo 1 > cpuset.mems stress --vm 1 --vm-bytes 12g --vm-hang 0 --------------- echo 2 > cpuset.mems stress --vm 1 --vm-bytes 12g --vm-hang 0 --------------- echo 3 > cpuset.mems stress --vm 1 --vm-bytes 12g --vm-hang 0 The retry trace look like: stress-2139 [003] ..... 666.934104: reclaim_retry_zone: node=1 zone=Normal order=0 reclaimable=7 available=7355 min_wmark=8598 no_progress_loops=1 wmark_check=0 stress-2204 [010] ..... 695.447393: reclaim_retry_zone: node=2 zone=Normal order=0 reclaimable=2 available=6916 min_wmark=8598 no_progress_loops=1 wmark_check=0 stress-2271 [008] ..... 725.683058: reclaim_retry_zone: node=3 zone=Normal order=0 reclaimable=17 available=8079 min_wmark=8597 no_progress_loops=1 wmark_check=0 With this patch, we can check the right node and get less retry in __alloc_pages_slowpath() because there is nothing to do. V1: Do the same with the page allocator using __cpuset_zone_allowed(). Suggested-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Zhongkun He <hezhongkun.hzk@bytedance.com> --- mm/compaction.c | 6 ++++++ mm/page_alloc.c | 5 +++++ 2 files changed, 11 insertions(+)