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memcgroup: tidy up mem_cgroup_charge_common 

Tidy up mem_cgroup_charge_common before extending it.  Adjust some comments,
but mainly clean up its loop: I've an aversion to loops full of continues,
then a break or a goto at the bottom.  And the is_atomic test should be on the
__GFP_WAIT bit, not GFP_ATOMIC bits.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Hugh Dickins 2008-02-07 00:14:19 -08:00 committed by Linus Torvalds
parent ac44d354d5
commit 3be91277e7
1 changed files with 15 additions and 29 deletions
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44
mm/memcontrol.c
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@ -345,23 +345,22 @@ retry:
goto done; goto done;
} }
} }
unlock_page_cgroup(page); unlock_page_cgroup(page);
pc = kzalloc(sizeof(struct page_cgroup), gfp_mask); pc = kzalloc(sizeof(struct page_cgroup), gfp_mask);
if (pc == NULL) if (pc == NULL)
goto err; goto err;
rcu_read_lock();
/* /*
* We always charge the cgroup the mm_struct belongs to * We always charge the cgroup the mm_struct belongs to.
* the mm_struct's mem_cgroup changes on task migration if the * The mm_struct's mem_cgroup changes on task migration if the
* thread group leader migrates. It's possible that mm is not * thread group leader migrates. It's possible that mm is not
* set, if so charge the init_mm (happens for pagecache usage). * set, if so charge the init_mm (happens for pagecache usage).
*/ */
if (!mm) if (!mm)
mm = &init_mm; mm = &init_mm;
rcu_read_lock();
mem = rcu_dereference(mm->mem_cgroup); mem = rcu_dereference(mm->mem_cgroup);
/* /*
* For every charge from the cgroup, increment reference * For every charge from the cgroup, increment reference
@ -375,12 +374,8 @@ retry:
* the cgroup limit. * the cgroup limit.
*/ */
while (res_counter_charge(&mem->res, PAGE_SIZE)) { while (res_counter_charge(&mem->res, PAGE_SIZE)) {
bool is_atomic = gfp_mask & GFP_ATOMIC; if (!(gfp_mask & __GFP_WAIT))
/* goto out;
* We cannot reclaim under GFP_ATOMIC, fail the charge
*/
if (is_atomic)
goto noreclaim;
if (try_to_free_mem_cgroup_pages(mem, gfp_mask)) if (try_to_free_mem_cgroup_pages(mem, gfp_mask))
continue; continue;
@ -394,23 +389,12 @@ retry:
*/ */
if (res_counter_check_under_limit(&mem->res)) if (res_counter_check_under_limit(&mem->res))
continue; continue;
/*
* Since we control both RSS and cache, we end up with a if (!nr_retries--) {
* very interesting scenario where we end up reclaiming mem_cgroup_out_of_memory(mem, gfp_mask);
* memory (essentially RSS), since the memory is pushed goto out;
* to swap cache, we eventually end up adding those
* pages back to our list. Hence we give ourselves a
* few chances before we fail
*/
else if (nr_retries--) {
congestion_wait(WRITE, HZ/10);
continue;
} }
noreclaim: congestion_wait(WRITE, HZ/10);
css_put(&mem->css);
if (!is_atomic)
mem_cgroup_out_of_memory(mem, GFP_KERNEL);
goto free_pc;
} }
atomic_set(&pc->ref_cnt, 1); atomic_set(&pc->ref_cnt, 1);
@ -419,10 +403,11 @@ noreclaim:
pc->flags = 0; pc->flags = 0;
if (ctype == MEM_CGROUP_CHARGE_TYPE_CACHE) if (ctype == MEM_CGROUP_CHARGE_TYPE_CACHE)
pc->flags |= PAGE_CGROUP_FLAG_CACHE; pc->flags |= PAGE_CGROUP_FLAG_CACHE;
if (page_cgroup_assign_new_page_cgroup(page, pc)) { if (page_cgroup_assign_new_page_cgroup(page, pc)) {
/* /*
* an another charge is added to this page already. * Another charge has been added to this page already.
* we do take lock_page_cgroup(page) again and read * We take lock_page_cgroup(page) again and read
* page->cgroup, increment refcnt.... just retry is OK. * page->cgroup, increment refcnt.... just retry is OK.
*/ */
res_counter_uncharge(&mem->res, PAGE_SIZE); res_counter_uncharge(&mem->res, PAGE_SIZE);
@ -437,7 +422,8 @@ noreclaim:
done: done:
return 0; return 0;
free_pc: out:
css_put(&mem->css);
kfree(pc); kfree(pc);
err: err:
return -ENOMEM; return -ENOMEM;