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Commit 519e5247 authored by Johannes Weiner's avatar Johannes Weiner Committed by Linus Torvalds
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mm: memcg: enable memcg OOM killer only for user faults 



System calls and kernel faults (uaccess, gup) can handle an out of memory
situation gracefully and just return -ENOMEM.

Enable the memcg OOM killer only for user faults, where it's really the
only option available.

Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: azurIt <azurit@pobox.sk>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3a13c4d7

include/linux/memcontrol.h

+44 −0
Original line number Diff line number Diff line
@@ -151,6 +151,37 @@ extern void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, 
extern void mem_cgroup_replace_page_cache(struct page *oldpage,

					struct page *newpage);



/**

 * mem_cgroup_toggle_oom - toggle the memcg OOM killer for the current task

 * @new: true to enable, false to disable

 *

 * Toggle whether a failed memcg charge should invoke the OOM killer

 * or just return -ENOMEM.  Returns the previous toggle state.

 */

static inline bool mem_cgroup_toggle_oom(bool new)

{

	bool old;



	old = current->memcg_oom.may_oom;

	current->memcg_oom.may_oom = new;



	return old;

}



static inline void mem_cgroup_enable_oom(void)

{

	bool old = mem_cgroup_toggle_oom(true);



	WARN_ON(old == true);

}



static inline void mem_cgroup_disable_oom(void)

{

	bool old = mem_cgroup_toggle_oom(false);



	WARN_ON(old == false);

}



#ifdef CONFIG_MEMCG_SWAP

extern int do_swap_account;

#endif
@@ -383,6 +414,19 @@ static inline void mem_cgroup_end_update_page_stat(struct page *page, 
{

}



static inline bool mem_cgroup_toggle_oom(bool new)

{

	return false;

}



static inline void mem_cgroup_enable_oom(void)

{

}



static inline void mem_cgroup_disable_oom(void)

{

}



static inline void mem_cgroup_inc_page_stat(struct page *page,

					    enum mem_cgroup_page_stat_item idx)

{

include/linux/sched.h

+3 −0
Original line number Diff line number Diff line
@@ -1393,6 +1393,9 @@ struct task_struct { 
		unsigned long memsw_nr_pages; /* uncharged mem+swap usage */

	} memcg_batch;

	unsigned int memcg_kmem_skip_account;

	struct memcg_oom_info {

		unsigned int may_oom:1;

	} memcg_oom;

#endif

#ifdef CONFIG_UPROBES

	struct uprobe_task *utask;

mm/filemap.c

+10 −1
Original line number Diff line number Diff line
@@ -1614,6 +1614,7 @@ int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 
	struct inode *inode = mapping->host;

	pgoff_t offset = vmf->pgoff;

	struct page *page;

	bool memcg_oom;

	pgoff_t size;

	int ret = 0;
@@ -1622,7 +1623,11 @@ int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 
		return VM_FAULT_SIGBUS;



	/*

	 * Do we have something in the page cache already?

	 * Do we have something in the page cache already?  Either

	 * way, try readahead, but disable the memcg OOM killer for it

	 * as readahead is optional and no errors are propagated up

	 * the fault stack.  The OOM killer is enabled while trying to

	 * instantiate the faulting page individually below.

	 */

	page = find_get_page(mapping, offset);

	if (likely(page) && !(vmf->flags & FAULT_FLAG_TRIED)) {
@@ -1630,10 +1635,14 @@ int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 
		 * We found the page, so try async readahead before

		 * waiting for the lock.

		 */

		memcg_oom = mem_cgroup_toggle_oom(false);

		do_async_mmap_readahead(vma, ra, file, page, offset);

		mem_cgroup_toggle_oom(memcg_oom);

	} else if (!page) {

		/* No page in the page cache at all */

		memcg_oom = mem_cgroup_toggle_oom(false);

		do_sync_mmap_readahead(vma, ra, file, offset);

		mem_cgroup_toggle_oom(memcg_oom);

		count_vm_event(PGMAJFAULT);

		mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);

		ret = VM_FAULT_MAJOR;

mm/memcontrol.c

+1 −1
Original line number Diff line number Diff line
@@ -2454,7 +2454,7 @@ static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, 
		return CHARGE_RETRY;



	/* If we don't need to call oom-killer at el, return immediately */

	if (!oom_check)

	if (!oom_check || !current->memcg_oom.may_oom)

		return CHARGE_NOMEM;

	/* check OOM */

	if (!mem_cgroup_handle_oom(mem_over_limit, gfp_mask, get_order(csize)))

mm/memory.c

+30 −10
Original line number Diff line number Diff line
@@ -3754,7 +3754,7 @@ int handle_pte_fault(struct mm_struct *mm, 
/*

 * By the time we get here, we already hold the mm semaphore

 */

int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,

static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,

			     unsigned long address, unsigned int flags)

{

	pgd_t *pgd;
@@ -3762,14 +3762,6 @@ int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, 
	pmd_t *pmd;

	pte_t *pte;



	__set_current_state(TASK_RUNNING);



	count_vm_event(PGFAULT);

	mem_cgroup_count_vm_event(mm, PGFAULT);



	/* do counter updates before entering really critical section. */

	check_sync_rss_stat(current);



	if (unlikely(is_vm_hugetlb_page(vma)))

		return hugetlb_fault(mm, vma, address, flags);
@@ -3850,6 +3842,34 @@ int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, 
	return handle_pte_fault(mm, vma, address, pte, pmd, flags);

}



int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,

		    unsigned long address, unsigned int flags)

{

	int ret;



	__set_current_state(TASK_RUNNING);



	count_vm_event(PGFAULT);

	mem_cgroup_count_vm_event(mm, PGFAULT);



	/* do counter updates before entering really critical section. */

	check_sync_rss_stat(current);



	/*

	 * Enable the memcg OOM handling for faults triggered in user

	 * space.  Kernel faults are handled more gracefully.

	 */

	if (flags & FAULT_FLAG_USER)

		mem_cgroup_enable_oom();



	ret = __handle_mm_fault(mm, vma, address, flags);



	if (flags & FAULT_FLAG_USER)

		mem_cgroup_disable_oom();



	return ret;

}



#ifndef __PAGETABLE_PUD_FOLDED

/*

 * Allocate page upper directory.