Messages in this thread Patch in this message | | | Subject | [rfc patch] sched/topology: fix domain reconstruction memory leakage | From | Mike Galbraith <> | Date | Sat, 19 Aug 2017 08:10:49 +0200 |
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Greetings,
While beating on cpu hotplug with the shiny new topology fixes backported, my memory poor 8 socket box fairly quickly leaked itself to death, 0c0e776a9b0f being the culprit. With the below applied, box took a severe beating overnight without a whimper.
I'm wondering (ergo rfc) if free_sched_groups() shouldn't be renamed to put_sched_groups() instead, with overlapping domains taking a group reference reference as well so they can put both sg/sgc rather than put one free the other. Those places that want an explicit free can pass free to only explicitly free sg (or use two functions). Minimalist approach works (minus signs, yay), but could perhaps use some "pretty".
sched/topology: fix domain reconstruction memory leakage
Since 0c0e776a9b0f, build_sched_groups() takes a reference on each sg and sgc during domain generation, where previously it only took a reference on the first group. Iterate groups and drop all added references during domain destruction, otherwise CPU hotplug leaks.
Signed-off-by: Mike Galbraith <mgalbraith@suse.de> Fixes: 0c0e776a9b0f ("sched/topology: Rewrite get_group()") --- kernel/sched/topology.c | 19 ++++++++----------- 1 file changed, 8 insertions(+), 11 deletions(-)
--- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -323,7 +323,7 @@ static struct root_domain *alloc_rootdom return rd; } -static void free_sched_groups(struct sched_group *sg, int free_sgc) +static void free_sched_groups(struct sched_group *sg, int put) { struct sched_group *tmp, *first; @@ -334,10 +334,11 @@ static void free_sched_groups(struct sch do { tmp = sg->next; - if (free_sgc && atomic_dec_and_test(&sg->sgc->ref)) + if (put && atomic_dec_and_test(&sg->sgc->ref)) kfree(sg->sgc); + if (put < 2 || atomic_dec_and_test(&sg->ref)) + kfree(sg); - kfree(sg); sg = tmp; } while (sg != first); } @@ -345,15 +346,11 @@ static void free_sched_groups(struct sch static void destroy_sched_domain(struct sched_domain *sd) { /* - * If its an overlapping domain it has private groups, iterate and - * nuke them all. + * If it's an overlapping domain it has private groups, iterate, + * freeing groups, otherwise dropping group references. In both + * cases, we must drop group capacity references. */ - if (sd->flags & SD_OVERLAP) { - free_sched_groups(sd->groups, 1); - } else if (atomic_dec_and_test(&sd->groups->ref)) { - kfree(sd->groups->sgc); - kfree(sd->groups); - } + free_sched_groups(sd->groups, !(sd->flags & SD_OVERLAP)+1); if (sd->shared && atomic_dec_and_test(&sd->shared->ref)) kfree(sd->shared); kfree(sd);
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