memcg: sanitize __mem_cgroup_try_charge() call protocol
Some callsites pass a memcg directly, some callsites pass an mm that then has to be translated to a memcg. This makes for a terrible function interface. Just push the mm-to-memcg translation into the respective callsites and always pass a memcg to mem_cgroup_try_charge(). [mhocko@suse.cz: add charge mm helper] Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Johannes Weiner
Linus Torvalds
parent
b6b6cc72bc
commit
6d1fdc4893
207
mm/memcontrol.c
207
mm/memcontrol.c
@ -2575,7 +2575,7 @@ static int memcg_cpu_hotplug_callback(struct notifier_block *nb,
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}
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/* See __mem_cgroup_try_charge() for details */
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/* See mem_cgroup_try_charge() for details */
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enum {
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CHARGE_OK, /* success */
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CHARGE_RETRY, /* need to retry but retry is not bad */
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@ -2648,45 +2648,34 @@ static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
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return CHARGE_NOMEM;
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}
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/*
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* __mem_cgroup_try_charge() does
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* 1. detect memcg to be charged against from passed *mm and *ptr,
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* 2. update res_counter
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* 3. call memory reclaim if necessary.
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/**
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* mem_cgroup_try_charge - try charging a memcg
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* @memcg: memcg to charge
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* @nr_pages: number of pages to charge
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* @oom: trigger OOM if reclaim fails
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*
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* In some special case, if the task is fatal, fatal_signal_pending() or
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* has TIF_MEMDIE, this function returns -EINTR while writing root_mem_cgroup
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* to *ptr. There are two reasons for this. 1: fatal threads should quit as soon
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* as possible without any hazards. 2: all pages should have a valid
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* pc->mem_cgroup. If mm is NULL and the caller doesn't pass a valid memcg
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* pointer, that is treated as a charge to root_mem_cgroup.
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*
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* So __mem_cgroup_try_charge() will return
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* 0 ... on success, filling *ptr with a valid memcg pointer.
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* -ENOMEM ... charge failure because of resource limits.
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* -EINTR ... if thread is fatal. *ptr is filled with root_mem_cgroup.
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*
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* Unlike the exported interface, an "oom" parameter is added. if oom==true,
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* the oom-killer can be invoked.
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* Returns 0 if @memcg was charged successfully, -EINTR if the charge
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* was bypassed to root_mem_cgroup, and -ENOMEM if the charge failed.
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*/
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static int __mem_cgroup_try_charge(struct mm_struct *mm,
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gfp_t gfp_mask,
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unsigned int nr_pages,
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struct mem_cgroup **ptr,
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bool oom)
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static int mem_cgroup_try_charge(struct mem_cgroup *memcg,
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gfp_t gfp_mask,
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unsigned int nr_pages,
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bool oom)
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{
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unsigned int batch = max(CHARGE_BATCH, nr_pages);
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int nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES;
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struct mem_cgroup *memcg = NULL;
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int ret;
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if (mem_cgroup_is_root(memcg))
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goto done;
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/*
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* Unlike gloval-vm's OOM-kill, we're not in memory shortage
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* in system level. So, allow to go ahead dying process in addition to
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* MEMDIE process.
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* Unlike in global OOM situations, memcg is not in a physical
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* memory shortage. Allow dying and OOM-killed tasks to
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* bypass the last charges so that they can exit quickly and
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* free their memory.
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*/
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if (unlikely(test_thread_flag(TIF_MEMDIE)
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|| fatal_signal_pending(current)))
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if (unlikely(test_thread_flag(TIF_MEMDIE) ||
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fatal_signal_pending(current)))
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goto bypass;
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if (unlikely(task_in_memcg_oom(current)))
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@ -2695,14 +2684,6 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm,
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if (gfp_mask & __GFP_NOFAIL)
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oom = false;
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again:
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if (*ptr) { /* css should be a valid one */
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memcg = *ptr;
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css_get(&memcg->css);
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} else {
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memcg = get_mem_cgroup_from_mm(mm);
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}
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if (mem_cgroup_is_root(memcg))
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goto done;
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if (consume_stock(memcg, nr_pages))
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goto done;
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@ -2710,10 +2691,8 @@ again:
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bool invoke_oom = oom && !nr_oom_retries;
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/* If killed, bypass charge */
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if (fatal_signal_pending(current)) {
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css_put(&memcg->css);
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if (fatal_signal_pending(current))
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goto bypass;
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}
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ret = mem_cgroup_do_charge(memcg, gfp_mask, batch,
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nr_pages, invoke_oom);
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@ -2722,17 +2701,12 @@ again:
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break;
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case CHARGE_RETRY: /* not in OOM situation but retry */
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batch = nr_pages;
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css_put(&memcg->css);
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memcg = NULL;
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goto again;
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case CHARGE_WOULDBLOCK: /* !__GFP_WAIT */
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css_put(&memcg->css);
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goto nomem;
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case CHARGE_NOMEM: /* OOM routine works */
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if (!oom || invoke_oom) {
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css_put(&memcg->css);
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if (!oom || invoke_oom)
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goto nomem;
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}
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nr_oom_retries--;
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break;
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}
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@ -2741,19 +2715,43 @@ again:
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if (batch > nr_pages)
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refill_stock(memcg, batch - nr_pages);
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done:
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css_put(&memcg->css);
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*ptr = memcg;
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return 0;
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nomem:
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if (!(gfp_mask & __GFP_NOFAIL)) {
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*ptr = NULL;
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if (!(gfp_mask & __GFP_NOFAIL))
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return -ENOMEM;
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}
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bypass:
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*ptr = root_mem_cgroup;
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return -EINTR;
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}
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/**
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* mem_cgroup_try_charge_mm - try charging a mm
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* @mm: mm_struct to charge
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* @nr_pages: number of pages to charge
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* @oom: trigger OOM if reclaim fails
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*
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* Returns the charged mem_cgroup associated with the given mm_struct or
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* NULL the charge failed.
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*/
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static struct mem_cgroup *mem_cgroup_try_charge_mm(struct mm_struct *mm,
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gfp_t gfp_mask,
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unsigned int nr_pages,
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bool oom)
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{
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struct mem_cgroup *memcg;
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int ret;
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memcg = get_mem_cgroup_from_mm(mm);
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ret = mem_cgroup_try_charge(memcg, gfp_mask, nr_pages, oom);
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css_put(&memcg->css);
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if (ret == -EINTR)
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memcg = root_mem_cgroup;
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else if (ret)
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memcg = NULL;
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return memcg;
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}
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/*
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* Somemtimes we have to undo a charge we got by try_charge().
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* This function is for that and do uncharge, put css's refcnt.
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@ -2949,20 +2947,17 @@ static int mem_cgroup_slabinfo_read(struct seq_file *m, void *v)
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static int memcg_charge_kmem(struct mem_cgroup *memcg, gfp_t gfp, u64 size)
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{
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struct res_counter *fail_res;
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struct mem_cgroup *_memcg;
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int ret = 0;
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ret = res_counter_charge(&memcg->kmem, size, &fail_res);
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if (ret)
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return ret;
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_memcg = memcg;
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ret = __mem_cgroup_try_charge(NULL, gfp, size >> PAGE_SHIFT,
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&_memcg, oom_gfp_allowed(gfp));
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ret = mem_cgroup_try_charge(memcg, gfp, size >> PAGE_SHIFT,
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oom_gfp_allowed(gfp));
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if (ret == -EINTR) {
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/*
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* __mem_cgroup_try_charge() chosed to bypass to root due to
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* mem_cgroup_try_charge() chosed to bypass to root due to
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* OOM kill or fatal signal. Since our only options are to
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* either fail the allocation or charge it to this cgroup, do
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* it as a temporary condition. But we can't fail. From a
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@ -2972,7 +2967,7 @@ static int memcg_charge_kmem(struct mem_cgroup *memcg, gfp_t gfp, u64 size)
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*
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* This condition will only trigger if the task entered
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* memcg_charge_kmem in a sane state, but was OOM-killed during
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* __mem_cgroup_try_charge() above. Tasks that were already
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* mem_cgroup_try_charge() above. Tasks that were already
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* dying when the allocation triggers should have been already
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* directed to the root cgroup in memcontrol.h
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*/
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@ -3826,10 +3821,9 @@ out:
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int mem_cgroup_newpage_charge(struct page *page,
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struct mm_struct *mm, gfp_t gfp_mask)
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{
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struct mem_cgroup *memcg = NULL;
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unsigned int nr_pages = 1;
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struct mem_cgroup *memcg;
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bool oom = true;
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int ret;
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if (mem_cgroup_disabled())
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return 0;
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@ -3848,9 +3842,9 @@ int mem_cgroup_newpage_charge(struct page *page,
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oom = false;
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}
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ret = __mem_cgroup_try_charge(mm, gfp_mask, nr_pages, &memcg, oom);
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if (ret == -ENOMEM)
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return ret;
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memcg = mem_cgroup_try_charge_mm(mm, gfp_mask, nr_pages, oom);
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if (!memcg)
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return -ENOMEM;
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__mem_cgroup_commit_charge(memcg, page, nr_pages,
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MEM_CGROUP_CHARGE_TYPE_ANON, false);
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return 0;
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@ -3867,7 +3861,7 @@ static int __mem_cgroup_try_charge_swapin(struct mm_struct *mm,
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gfp_t mask,
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struct mem_cgroup **memcgp)
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{
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struct mem_cgroup *memcg;
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struct mem_cgroup *memcg = NULL;
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struct page_cgroup *pc;
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int ret;
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@ -3880,31 +3874,29 @@ static int __mem_cgroup_try_charge_swapin(struct mm_struct *mm,
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* in turn serializes uncharging.
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*/
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if (PageCgroupUsed(pc))
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return 0;
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if (!do_swap_account)
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goto charge_cur_mm;
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memcg = try_get_mem_cgroup_from_page(page);
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goto out;
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if (do_swap_account)
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memcg = try_get_mem_cgroup_from_page(page);
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if (!memcg)
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goto charge_cur_mm;
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*memcgp = memcg;
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ret = __mem_cgroup_try_charge(NULL, mask, 1, memcgp, true);
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memcg = get_mem_cgroup_from_mm(mm);
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ret = mem_cgroup_try_charge(memcg, mask, 1, true);
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css_put(&memcg->css);
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if (ret == -EINTR)
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ret = 0;
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return ret;
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charge_cur_mm:
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ret = __mem_cgroup_try_charge(mm, mask, 1, memcgp, true);
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if (ret == -EINTR)
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ret = 0;
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return ret;
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memcg = root_mem_cgroup;
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else if (ret)
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return ret;
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out:
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*memcgp = memcg;
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return 0;
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}
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int mem_cgroup_try_charge_swapin(struct mm_struct *mm, struct page *page,
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gfp_t gfp_mask, struct mem_cgroup **memcgp)
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{
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*memcgp = NULL;
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if (mem_cgroup_disabled())
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if (mem_cgroup_disabled()) {
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*memcgp = NULL;
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return 0;
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}
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/*
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* A racing thread's fault, or swapoff, may have already
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* updated the pte, and even removed page from swap cache: in
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@ -3912,12 +3904,13 @@ int mem_cgroup_try_charge_swapin(struct mm_struct *mm, struct page *page,
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* there's also a KSM case which does need to charge the page.
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*/
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if (!PageSwapCache(page)) {
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int ret;
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struct mem_cgroup *memcg;
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ret = __mem_cgroup_try_charge(mm, gfp_mask, 1, memcgp, true);
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if (ret == -EINTR)
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ret = 0;
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return ret;
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memcg = mem_cgroup_try_charge_mm(mm, gfp_mask, 1, true);
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if (!memcg)
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return -ENOMEM;
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*memcgp = memcg;
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return 0;
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}
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return __mem_cgroup_try_charge_swapin(mm, page, gfp_mask, memcgp);
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}
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@ -3964,8 +3957,8 @@ void mem_cgroup_commit_charge_swapin(struct page *page,
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int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
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gfp_t gfp_mask)
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{
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struct mem_cgroup *memcg = NULL;
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enum charge_type type = MEM_CGROUP_CHARGE_TYPE_CACHE;
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struct mem_cgroup *memcg;
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int ret;
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if (mem_cgroup_disabled())
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@ -3973,23 +3966,28 @@ int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
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if (PageCompound(page))
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return 0;
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if (!PageSwapCache(page)) {
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/*
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* Page cache insertions can happen without an actual
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* task context, e.g. during disk probing on boot.
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*/
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if (!mm)
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memcg = root_mem_cgroup;
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ret = __mem_cgroup_try_charge(mm, gfp_mask, 1, &memcg, true);
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if (ret != -ENOMEM)
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__mem_cgroup_commit_charge(memcg, page, 1, type, false);
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} else { /* page is swapcache/shmem */
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if (PageSwapCache(page)) { /* shmem */
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ret = __mem_cgroup_try_charge_swapin(mm, page,
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gfp_mask, &memcg);
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if (!ret)
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__mem_cgroup_commit_charge_swapin(page, memcg, type);
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if (ret)
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return ret;
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__mem_cgroup_commit_charge_swapin(page, memcg, type);
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return 0;
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}
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return ret;
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/*
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* Page cache insertions can happen without an actual mm
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* context, e.g. during disk probing on boot.
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*/
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if (unlikely(!mm))
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memcg = root_mem_cgroup;
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else {
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memcg = mem_cgroup_try_charge_mm(mm, gfp_mask, 1, true);
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if (!memcg)
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return -ENOMEM;
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}
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__mem_cgroup_commit_charge(memcg, page, 1, type, false);
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return 0;
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}
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static void mem_cgroup_do_uncharge(struct mem_cgroup *memcg,
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@ -6601,8 +6599,7 @@ one_by_one:
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batch_count = PRECHARGE_COUNT_AT_ONCE;
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cond_resched();
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}
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ret = __mem_cgroup_try_charge(NULL,
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GFP_KERNEL, 1, &memcg, false);
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ret = mem_cgroup_try_charge(memcg, GFP_KERNEL, 1, false);
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if (ret)
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/* mem_cgroup_clear_mc() will do uncharge later */
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return ret;
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