(2012/04/21 6:57), Glauber Costa wrote: > From: Suleiman Souhlal <[email protected]> > > mem_cgroup_do_charge() was written before slab accounting, and expects > three cases: being called for 1 page, being called for a stock of 32 pages, > or being called for a hugepage. If we call for 2 pages (and several slabs > used in process creation are such, at least with the debug options I had), > it assumed it's being called for stock and just retried without reclaiming. > > Fix that by passing down a minsize argument in addition to the csize. > > And what to do about that (csize == PAGE_SIZE && ret) retry? If it's > needed at all (and presumably is since it's there, perhaps to handle > races), then it should be extended to more than PAGE_SIZE, yet how far?
IIRC, it was for preventing rapid OOM kill and reducing latency. > And should there be a retry count limit, of what? For now retry up to > COSTLY_ORDER (as page_alloc.c does), stay safe with a cond_resched(), > and make sure not to do it if __GFP_NORETRY. > > Signed-off-by: Suleiman Souhlal <[email protected]> Hmm, maybe ok. Reviewed-by: KAMEZAWA Hiroyuki <[email protected]> > --- > mm/memcontrol.c | 18 +++++++++++------- > 1 files changed, 11 insertions(+), 7 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 4b94b2d..cbffc4c 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -2187,7 +2187,8 @@ enum { > }; > > static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, > - unsigned int nr_pages, bool oom_check) > + unsigned int nr_pages, unsigned int min_pages, > + bool oom_check) > { > unsigned long csize = nr_pages * PAGE_SIZE; > struct mem_cgroup *mem_over_limit; > @@ -2210,18 +2211,18 @@ static int mem_cgroup_do_charge(struct mem_cgroup > *memcg, gfp_t gfp_mask, > } else > mem_over_limit = mem_cgroup_from_res_counter(fail_res, res); > /* > - * nr_pages can be either a huge page (HPAGE_PMD_NR), a batch > - * of regular pages (CHARGE_BATCH), or a single regular page (1). > - * > * Never reclaim on behalf of optional batching, retry with a > * single page instead. > */ > - if (nr_pages == CHARGE_BATCH) > + if (nr_pages > min_pages) > return CHARGE_RETRY; > > if (!(gfp_mask & __GFP_WAIT)) > return CHARGE_WOULDBLOCK; > > + if (gfp_mask & __GFP_NORETRY) > + return CHARGE_NOMEM; > + > ret = mem_cgroup_reclaim(mem_over_limit, gfp_mask, flags); > if (mem_cgroup_margin(mem_over_limit) >= nr_pages) > return CHARGE_RETRY; > @@ -2234,8 +2235,10 @@ static int mem_cgroup_do_charge(struct mem_cgroup > *memcg, gfp_t gfp_mask, > * unlikely to succeed so close to the limit, and we fall back > * to regular pages anyway in case of failure. > */ > - if (nr_pages == 1 && ret) > + if (nr_pages <= (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER) && ret) { > + cond_resched(); > return CHARGE_RETRY; > + } > > /* > * At task move, charge accounts can be doubly counted. So, it's > @@ -2369,7 +2372,8 @@ again: > nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES; > } > > - ret = mem_cgroup_do_charge(memcg, gfp_mask, batch, oom_check); > + ret = mem_cgroup_do_charge(memcg, gfp_mask, batch, nr_pages, > + oom_check); > switch (ret) { > case CHARGE_OK: > break; _______________________________________________ Devel mailing list [email protected] https://openvz.org/mailman/listinfo/devel
