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mm/vmscan.c: add checks for incorrect handling of current->reclaim_state 

Six sites are presently altering current->reclaim_state.  There is a
risk that one function stomps on a caller's value.  Use a helper
function to catch such errors.

Cc: Yafang Shao <laoar.shao@gmail.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrew Morton 2019-07-16 16:26:15 -07:00 committed by Linus Torvalds
parent 0308f7cf19
commit 1732d2b011
1 changed files with 24 additions and 13 deletions
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37
mm/vmscan.c
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@ -241,6 +241,18 @@ static void unregister_memcg_shrinker(struct shrinker *shrinker)
}
#endif /* CONFIG_MEMCG_KMEM */
static void set_task_reclaim_state(struct task_struct *task,
struct reclaim_state *rs)
{
/* Check for an overwrite */
WARN_ON_ONCE(rs && task->reclaim_state);
/* Check for the nulling of an already-nulled member */
WARN_ON_ONCE(!rs && !task->reclaim_state);
task->reclaim_state = rs;
}
#ifdef CONFIG_MEMCG
static bool global_reclaim(struct scan_control *sc)
{
@ -3194,13 +3206,13 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
if (throttle_direct_reclaim(sc.gfp_mask, zonelist, nodemask))
return 1;
current->reclaim_state = &sc.reclaim_state;
set_task_reclaim_state(current, &sc.reclaim_state);
trace_mm_vmscan_direct_reclaim_begin(order, sc.gfp_mask);
nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
trace_mm_vmscan_direct_reclaim_end(nr_reclaimed);
current->reclaim_state = NULL;
set_task_reclaim_state(current, NULL);
return nr_reclaimed;
}
@ -3223,7 +3235,7 @@ unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,
};
unsigned long lru_pages;
current->reclaim_state = &sc.reclaim_state;
set_task_reclaim_state(current, &sc.reclaim_state);
sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
(GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
@ -3241,7 +3253,7 @@ unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,
trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed);
current->reclaim_state = NULL;
set_task_reclaim_state(current, NULL);
*nr_scanned = sc.nr_scanned;
return sc.nr_reclaimed;
@ -3270,7 +3282,7 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
.may_shrinkslab = 1,
};
current->reclaim_state = &sc.reclaim_state;
set_task_reclaim_state(current, &sc.reclaim_state);
/*
* Unlike direct reclaim via alloc_pages(), memcg's reclaim doesn't
* take care of from where we get pages. So the node where we start the
@ -3291,7 +3303,7 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
psi_memstall_leave(&pflags);
trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed);
current->reclaim_state = NULL;
set_task_reclaim_state(current, NULL);
return nr_reclaimed;
}
@ -3493,7 +3505,7 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)
.may_unmap = 1,
};
current->reclaim_state = &sc.reclaim_state;
set_task_reclaim_state(current, &sc.reclaim_state);
psi_memstall_enter(&pflags);
__fs_reclaim_acquire();
@ -3675,7 +3687,7 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)
snapshot_refaults(NULL, pgdat);
__fs_reclaim_release();
psi_memstall_leave(&pflags);
current->reclaim_state = NULL;
set_task_reclaim_state(current, NULL);
/*
* Return the order kswapd stopped reclaiming at as
@ -3940,17 +3952,16 @@ unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
.hibernation_mode = 1,
};
struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask);
struct task_struct *p = current;
unsigned long nr_reclaimed;
unsigned int noreclaim_flag;
fs_reclaim_acquire(sc.gfp_mask);
noreclaim_flag = memalloc_noreclaim_save();
p->reclaim_state = &sc.reclaim_state;
set_task_reclaim_state(current, &sc.reclaim_state);
nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
p->reclaim_state = NULL;
set_task_reclaim_state(current, NULL);
memalloc_noreclaim_restore(noreclaim_flag);
fs_reclaim_release(sc.gfp_mask);
@ -4139,7 +4150,7 @@ static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned in
*/
noreclaim_flag = memalloc_noreclaim_save();
p->flags |= PF_SWAPWRITE;
p->reclaim_state = &sc.reclaim_state;
set_task_reclaim_state(p, &sc.reclaim_state);
if (node_pagecache_reclaimable(pgdat) > pgdat->min_unmapped_pages) {
/*
@ -4151,7 +4162,7 @@ static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned in
} while (sc.nr_reclaimed < nr_pages && --sc.priority >= 0);
}
p->reclaim_state = NULL;
set_task_reclaim_state(p, NULL);
current->flags &= ~PF_SWAPWRITE;
memalloc_noreclaim_restore(noreclaim_flag);
fs_reclaim_release(sc.gfp_mask);