The patch titled
Subject: memcg: return -EINTR at bypassing try_charge()
has been removed from the -mm tree. Its filename was
memcg-simplify-lru-handling-by-new-rule-memcg-return-eintr-at-bypassing-try_charge.patch
This patch was dropped because it was folded into memcg-simplify-lru-handling-by-new-rule.patch
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Subject: memcg: return -EINTR at bypassing try_charge()
This patch is a fix for memcg-simplify-lru-handling-by-new-rule.patch
When running testprogram and stop it by Ctrl-C, add_lru/del_lru
will find pc->mem_cgroup is NULL and get panic. The reason
is bypass code in try_charge().
At try_charge(), it checks the thread is fatal or not as..
fatal_signal_pending() or TIF_MEMDIE. In this case, __try_charge()
returns 0(success) with setting *ptr as NULL.
Now, lruvec are deteremined by pc->mem_cgroup. So, it's better
to reset pc->mem_cgroup as root_mem_cgroup. This patch does
following change in try_charge()
1. return -EINTR at bypassing.
2. set *ptr = root_mem_cgroup at bypassing.
By this change, in page fault / radix-tree-insert path,
the page will be charged against root_mem_cgroup and the thread's
operations will go ahead without trouble. In other path,
migration or move_account etc..., -EINTR will stop the operation.
(may need some cleanup later..)
After this change, pc->mem_cgroup will have valid pointer if
the page is used.
Changelog: v2 -> v3
- handle !mm case in another way.
- removed redundant commments
- fixed move_parent bug of uninitialized pointer
Changelog: v1 -> v2
- returns -EINTR at bypassing.
- change error code handling at callers.
- changed the name of patch.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxx>
Cc: Miklos Szeredi <mszeredi@xxxxxxx>
Cc: Ying Han <yinghan@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 45 ++++++++++++++++++++++++++++++++++-----------
1 file changed, 34 insertions(+), 11 deletions(-)
diff -puN mm/memcontrol.c~memcg-simplify-lru-handling-by-new-rule-memcg-return-eintr-at-bypassing-try_charge mm/memcontrol.c
--- a/mm/memcontrol.c~memcg-simplify-lru-handling-by-new-rule-memcg-return-eintr-at-bypassing-try_charge
+++ a/mm/memcontrol.c
@@ -2184,6 +2184,24 @@ static int mem_cgroup_do_charge(struct m
}
/*
+ * __mem_cgroup_try_charge() does
+ * 1. detect memcg to be charged against from passed *mm and *ptr,
+ * 2. update res_counter
+ * 3. call memory reclaim if necessary.
+ *
+ * In some special case, if the task is fatal, fatal_signal_pending() or
+ * TIF_MEMDIE, this functoion returns -EINTR with filling *ptr as
+ * root_mem_cgroup. There are 2 reasons for this. 1st is that
+ * fatal threads should quit as soon as possible without any hazards.
+ * 2nd is that all page should have valid pc->mem_cgroup if it will be
+ * used. If mm is NULL and the caller doesn't pass valid memcg pointer,
+ * that's treated as charge to root_mem_cgroup.
+ *
+ * So, try_charge will return
+ * 0 ... at success. filling *ptr with a valid memcg pointer.
+ * -ENOMEM ... charge failure because of resource limits.
+ * -EINTR ... if thread is fatal. *ptr is filled with root_mem_cgroup.
+ *
* Unlike exported interface, "oom" parameter is added. if oom==true,
* oom-killer can be invoked.
*/
@@ -2214,7 +2232,7 @@ static int __mem_cgroup_try_charge(struc
* set, if so charge the init_mm (happens for pagecache usage).
*/
if (!*ptr && !mm)
- goto bypass;
+ *ptr = root_mem_cgroup;
again:
if (*ptr) { /* css should be a valid one */
memcg = *ptr;
@@ -2315,8 +2333,8 @@ nomem:
*ptr = NULL;
return -ENOMEM;
bypass:
- *ptr = NULL;
- return 0;
+ *ptr = root_mem_cgroup;
+ return -EINTR;
}
/*
@@ -2582,7 +2600,7 @@ static int mem_cgroup_move_parent(struct
parent = mem_cgroup_from_cont(pcg);
ret = __mem_cgroup_try_charge(NULL, gfp_mask, nr_pages, &parent, false);
- if (ret || !parent)
+ if (ret)
goto put_back;
if (nr_pages > 1)
@@ -2629,9 +2647,8 @@ static int mem_cgroup_charge_common(stru
pc = lookup_page_cgroup(page);
ret = __mem_cgroup_try_charge(mm, gfp_mask, nr_pages, &memcg, oom);
- if (ret || !memcg)
+ if (ret == -ENOMEM)
return ret;
-
__mem_cgroup_commit_charge(memcg, page, nr_pages, pc, ctype);
return 0;
}
@@ -2742,11 +2759,16 @@ int mem_cgroup_try_charge_swapin(struct
*memcgp = memcg;
ret = __mem_cgroup_try_charge(NULL, mask, 1, memcgp, true);
css_put(&memcg->css);
+ if (ret == -EINTR)
+ ret = 0;
return ret;
charge_cur_mm:
if (unlikely(!mm))
mm = &init_mm;
- return __mem_cgroup_try_charge(mm, mask, 1, memcgp, true);
+ ret = __mem_cgroup_try_charge(mm, mask, 1, memcgp, true);
+ if (ret == -EINTR)
+ ret = 0;
+ return ret;
}
static void
@@ -3206,7 +3228,7 @@ int mem_cgroup_prepare_migration(struct
*memcgp = memcg;
ret = __mem_cgroup_try_charge(NULL, gfp_mask, 1, memcgp, false);
css_put(&memcg->css);/* drop extra refcnt */
- if (ret || *memcgp == NULL) {
+ if (ret) {
if (PageAnon(page)) {
lock_page_cgroup(pc);
ClearPageCgroupMigration(pc);
@@ -3216,6 +3238,7 @@ int mem_cgroup_prepare_migration(struct
*/
mem_cgroup_uncharge_page(page);
}
+ /* we'll need to revisit this error code (we have -EINTR) */
return -ENOMEM;
}
/*
@@ -3635,7 +3658,7 @@ static int mem_cgroup_force_empty_list(s
pc = lookup_page_cgroup(page);
ret = mem_cgroup_move_parent(page, pc, memcg, GFP_KERNEL);
- if (ret == -ENOMEM)
+ if (ret == -ENOMEM || ret == -EINTR)
break;
if (ret == -EBUSY || ret == -EINVAL) {
@@ -5026,9 +5049,9 @@ one_by_one:
}
ret = __mem_cgroup_try_charge(NULL,
GFP_KERNEL, 1, &memcg, false);
- if (ret || !memcg)
+ if (ret)
/* mem_cgroup_clear_mc() will do uncharge later */
- return -ENOMEM;
+ return ret;
mc.precharge++;
}
return ret;
_
Patches currently in -mm which might be from kamezawa.hiroyu@xxxxxxxxxxxxxx are
origin.patch
memcg-add-mem_cgroup_replace_page_cache-to-fix-lru-issue.patch
mm-memcg-consolidate-hierarchy-iteration-primitives.patch
mm-vmscan-distinguish-global-reclaim-from-global-lru-scanning.patch
mm-vmscan-distinguish-between-memcg-triggering-reclaim-and-memcg-being-scanned.patch
mm-memcg-per-priority-per-zone-hierarchy-scan-generations.patch
mm-move-memcg-hierarchy-reclaim-to-generic-reclaim-code.patch
mm-memcg-remove-optimization-of-keeping-the-root_mem_cgroup-lru-lists-empty.patch
mm-vmscan-convert-global-reclaim-to-per-memcg-lru-lists.patch
mm-collect-lru-list-heads-into-struct-lruvec.patch
mm-make-per-memcg-lru-lists-exclusive.patch
mm-memcg-remove-unused-node-section-info-from-pc-flags.patch
memcg-make-mem_cgroup_split_huge_fixup-more-efficient.patch
mm-memcg-shorten-preempt-disabled-section-around-event-checks.patch
documentation-cgroups-memorytxt-fix-typo.patch
memcg-fix-pgpgin-pgpgout-documentation.patch
mm-oom_kill-remove-memcg-argument-from-oom_kill_task.patch
mm-unify-remaining-mem_cont-mem-etc-variable-names-to-memcg.patch
mm-memcg-clean-up-fault-accounting.patch
mm-memcg-lookup_page_cgroup-almost-never-returns-null.patch
mm-page_cgroup-check-page_cgroup-arrays-in-lookup_page_cgroup-only-when-necessary.patch
mm-memcg-remove-unneeded-checks-from-newpage_charge.patch
mm-memcg-remove-unneeded-checks-from-uncharge_page.patch
page_cgroup-add-helper-function-to-get-swap_cgroup.patch
memcg-clean-up-soft_limit_tree-if-allocation-fails.patch
oom-memcg-fix-exclusion-of-memcg-threads-after-they-have-detached-their-mm.patch
memcg-simplify-page-cache-charging.patch
memcg-simplify-corner-case-handling-of-lru.patch
memcg-clear-pc-mem_cgorup-if-necessary.patch
memcg-simplify-lru-handling-by-new-rule.patch
memcg-simplify-lru-handling-by-new-rule-memcg-return-eintr-at-bypassing-try_charge-fix.patch
memcg-simplify-lru-handling-by-new-rule-memcg-return-eintr-at-bypassing-try_charge-fix-null-mem_cgroup_try_charge.patch
memcg-cleanup-for_each_node_state.patch
page_alloc-break-early-in-check_for_regular_memory.patch
page_cgroup-drop-multi-config_memory_hotplug.patch
vmscan-trace-add-file-info-to-trace_mm_vmscan_lru_isolate.patch
memcg-fix-split_huge_page_refcounts.patch
memcg-fix-mem_cgroup_print_bad_page.patch
mm-take-pagevecs-off-reclaim-stack.patch
c-r-introduce-checkpoint_restore-symbol.patch
c-r-procfs-add-start_data-end_data-start_brk-members-to-proc-pid-stat-v4.patch
c-r-procfs-add-start_data-end_data-start_brk-members-to-proc-pid-stat-v4-fix.patch
c-r-prctl-add-pr_set_mm-codes-to-set-up-mm_struct-entries.patch
c-r-prctl-add-pr_set_mm-codes-to-set-up-mm_struct-entries-fix.patch
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