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authorVlastimil Babka <vbabka@suse.cz>2017-05-08 15:59:50 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-05-08 17:15:15 -0700
commit499118e966f1d2150bd66647c8932343c4e9a0b8 (patch)
treecc3560705304d978526ecffa055066b2c8b09fa6 /mm/vmscan.c
parent62be1511b1db8066220b18b7d4da2e6b9fdc69fb (diff)
downloadlinux-499118e966f1d2150bd66647c8932343c4e9a0b8.tar.bz2
mm: introduce memalloc_noreclaim_{save,restore}
The previous patch ("mm: prevent potential recursive reclaim due to clearing PF_MEMALLOC") has shown that simply setting and clearing PF_MEMALLOC in current->flags can result in wrongly clearing a pre-existing PF_MEMALLOC flag and potentially lead to recursive reclaim. Let's introduce helpers that support proper nesting by saving the previous stat of the flag, similar to the existing memalloc_noio_* and memalloc_nofs_* helpers. Convert existing setting/clearing of PF_MEMALLOC within mm to the new helpers. There are no known issues with the converted code, but the change makes it more robust. Link: http://lkml.kernel.org/r/20170405074700.29871-3-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Suggested-by: Michal Hocko <mhocko@suse.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Boris Brezillon <boris.brezillon@free-electrons.com> Cc: Chris Leech <cleech@redhat.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Eric Dumazet <edumazet@google.com> Cc: Josef Bacik <jbacik@fb.com> Cc: Lee Duncan <lduncan@suse.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Richard Weinberger <richard@nod.at> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/vmscan.c')
-rw-r--r--mm/vmscan.c17
1 files changed, 11 insertions, 6 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 4e7ed65842af..2f45c0520f43 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3036,6 +3036,7 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
struct zonelist *zonelist;
unsigned long nr_reclaimed;
int nid;
+ unsigned int noreclaim_flag;
struct scan_control sc = {
.nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX),
.gfp_mask = (current_gfp_context(gfp_mask) & GFP_RECLAIM_MASK) |
@@ -3062,9 +3063,9 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
sc.gfp_mask,
sc.reclaim_idx);
- current->flags |= PF_MEMALLOC;
+ noreclaim_flag = memalloc_noreclaim_save();
nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
- current->flags &= ~PF_MEMALLOC;
+ memalloc_noreclaim_restore(noreclaim_flag);
trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed);
@@ -3589,8 +3590,9 @@ unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask);
struct task_struct *p = current;
unsigned long nr_reclaimed;
+ unsigned int noreclaim_flag;
- p->flags |= PF_MEMALLOC;
+ noreclaim_flag = memalloc_noreclaim_save();
lockdep_set_current_reclaim_state(sc.gfp_mask);
reclaim_state.reclaimed_slab = 0;
p->reclaim_state = &reclaim_state;
@@ -3599,7 +3601,7 @@ unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
p->reclaim_state = NULL;
lockdep_clear_current_reclaim_state();
- p->flags &= ~PF_MEMALLOC;
+ memalloc_noreclaim_restore(noreclaim_flag);
return nr_reclaimed;
}
@@ -3764,6 +3766,7 @@ static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned in
struct task_struct *p = current;
struct reclaim_state reclaim_state;
int classzone_idx = gfp_zone(gfp_mask);
+ unsigned int noreclaim_flag;
struct scan_control sc = {
.nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX),
.gfp_mask = (gfp_mask = current_gfp_context(gfp_mask)),
@@ -3781,7 +3784,8 @@ static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned in
* and we also need to be able to write out pages for RECLAIM_WRITE
* and RECLAIM_UNMAP.
*/
- p->flags |= PF_MEMALLOC | PF_SWAPWRITE;
+ noreclaim_flag = memalloc_noreclaim_save();
+ p->flags |= PF_SWAPWRITE;
lockdep_set_current_reclaim_state(gfp_mask);
reclaim_state.reclaimed_slab = 0;
p->reclaim_state = &reclaim_state;
@@ -3797,7 +3801,8 @@ static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned in
}
p->reclaim_state = NULL;
- current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE);
+ current->flags &= ~PF_SWAPWRITE;
+ memalloc_noreclaim_restore(noreclaim_flag);
lockdep_clear_current_reclaim_state();
return sc.nr_reclaimed >= nr_pages;
}