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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>
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0308f7cf19
commit
1732d2b011
37
mm/vmscan.c
37
mm/vmscan.c
@ -241,6 +241,18 @@ static void unregister_memcg_shrinker(struct shrinker *shrinker)
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}
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#endif /* CONFIG_MEMCG_KMEM */
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static void set_task_reclaim_state(struct task_struct *task,
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struct reclaim_state *rs)
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{
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/* Check for an overwrite */
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WARN_ON_ONCE(rs && task->reclaim_state);
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/* Check for the nulling of an already-nulled member */
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WARN_ON_ONCE(!rs && !task->reclaim_state);
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task->reclaim_state = rs;
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}
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#ifdef CONFIG_MEMCG
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static bool global_reclaim(struct scan_control *sc)
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{
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@ -3194,13 +3206,13 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
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if (throttle_direct_reclaim(sc.gfp_mask, zonelist, nodemask))
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return 1;
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current->reclaim_state = &sc.reclaim_state;
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set_task_reclaim_state(current, &sc.reclaim_state);
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trace_mm_vmscan_direct_reclaim_begin(order, sc.gfp_mask);
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nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
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trace_mm_vmscan_direct_reclaim_end(nr_reclaimed);
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current->reclaim_state = NULL;
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set_task_reclaim_state(current, NULL);
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return nr_reclaimed;
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}
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@ -3223,7 +3235,7 @@ unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,
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};
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unsigned long lru_pages;
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current->reclaim_state = &sc.reclaim_state;
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set_task_reclaim_state(current, &sc.reclaim_state);
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sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
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(GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
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@ -3241,7 +3253,7 @@ unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,
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trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed);
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current->reclaim_state = NULL;
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set_task_reclaim_state(current, NULL);
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*nr_scanned = sc.nr_scanned;
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return sc.nr_reclaimed;
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@ -3270,7 +3282,7 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
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.may_shrinkslab = 1,
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};
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current->reclaim_state = &sc.reclaim_state;
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set_task_reclaim_state(current, &sc.reclaim_state);
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/*
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* Unlike direct reclaim via alloc_pages(), memcg's reclaim doesn't
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* take care of from where we get pages. So the node where we start the
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@ -3291,7 +3303,7 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
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psi_memstall_leave(&pflags);
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trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed);
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current->reclaim_state = NULL;
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set_task_reclaim_state(current, NULL);
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return nr_reclaimed;
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}
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@ -3493,7 +3505,7 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)
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.may_unmap = 1,
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};
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current->reclaim_state = &sc.reclaim_state;
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set_task_reclaim_state(current, &sc.reclaim_state);
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psi_memstall_enter(&pflags);
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__fs_reclaim_acquire();
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@ -3675,7 +3687,7 @@ out:
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snapshot_refaults(NULL, pgdat);
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__fs_reclaim_release();
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psi_memstall_leave(&pflags);
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current->reclaim_state = NULL;
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set_task_reclaim_state(current, NULL);
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/*
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* Return the order kswapd stopped reclaiming at as
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@ -3940,17 +3952,16 @@ unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
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.hibernation_mode = 1,
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};
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struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask);
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struct task_struct *p = current;
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unsigned long nr_reclaimed;
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unsigned int noreclaim_flag;
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fs_reclaim_acquire(sc.gfp_mask);
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noreclaim_flag = memalloc_noreclaim_save();
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p->reclaim_state = &sc.reclaim_state;
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set_task_reclaim_state(current, &sc.reclaim_state);
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nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
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p->reclaim_state = NULL;
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set_task_reclaim_state(current, NULL);
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memalloc_noreclaim_restore(noreclaim_flag);
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fs_reclaim_release(sc.gfp_mask);
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@ -4139,7 +4150,7 @@ static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned in
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*/
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noreclaim_flag = memalloc_noreclaim_save();
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p->flags |= PF_SWAPWRITE;
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p->reclaim_state = &sc.reclaim_state;
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set_task_reclaim_state(p, &sc.reclaim_state);
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if (node_pagecache_reclaimable(pgdat) > pgdat->min_unmapped_pages) {
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/*
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@ -4151,7 +4162,7 @@ static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned in
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} while (sc.nr_reclaimed < nr_pages && --sc.priority >= 0);
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}
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p->reclaim_state = NULL;
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set_task_reclaim_state(p, NULL);
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current->flags &= ~PF_SWAPWRITE;
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memalloc_noreclaim_restore(noreclaim_flag);
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fs_reclaim_release(sc.gfp_mask);
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