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mm: memcontrol: switch to native NR_ANON_MAPPED counter
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Memcg maintains a private MEMCG_RSS counter.  This divergence from the
generic VM accounting means unnecessary code overhead, and creates a
dependency for memcg that page->mapping is set up at the time of charging,
so that page types can be told apart.

Convert the generic accounting sites to mod_lruvec_page_state and friends
to maintain the per-cgroup vmstat counter of NR_ANON_MAPPED.  We use
lock_page_memcg() to stabilize page->mem_cgroup during rmap changes, the
same way we do for NR_FILE_MAPPED.

With the previous patch removing MEMCG_CACHE and the private NR_SHMEM
counter, this patch finally eliminates the need to have page->mapping set
up at charge time.  However, we need to have page->mem_cgroup set up by
the time rmap runs and does the accounting, so switch the commit and the
rmap callbacks around.

v2: fix temporary accounting bug by switching rmap<->commit (Joonsoo)

Signed-off-by: Johannes Weiner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Cc: Alex Shi <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: "Kirill A. Shutemov" <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Shakeel Butt <[email protected]>
Cc: Balbir Singh <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>
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hnaz authored and torvalds committed Jun 4, 2020
1 parent 0d1c207 commit be5d0a7
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Showing 10 changed files with 51 additions and 50 deletions.
3 changes: 1 addition & 2 deletions include/linux/memcontrol.h
Original file line number Diff line number Diff line change
Expand Up @@ -29,8 +29,7 @@ struct kmem_cache;

/* Cgroup-specific page state, on top of universal node page state */
enum memcg_stat_item {
MEMCG_RSS = NR_VM_NODE_STAT_ITEMS,
MEMCG_RSS_HUGE,
MEMCG_RSS_HUGE = NR_VM_NODE_STAT_ITEMS,
MEMCG_SWAP,
MEMCG_SOCK,
/* XXX: why are these zone and not node counters? */
Expand Down
2 changes: 1 addition & 1 deletion kernel/events/uprobes.c
Original file line number Diff line number Diff line change
Expand Up @@ -188,8 +188,8 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,

if (new_page) {
get_page(new_page);
page_add_new_anon_rmap(new_page, vma, addr, false);
mem_cgroup_commit_charge(new_page, memcg, false);
page_add_new_anon_rmap(new_page, vma, addr, false);
lru_cache_add_active_or_unevictable(new_page, vma);
} else
/* no new page, just dec_mm_counter for old_page */
Expand Down
2 changes: 1 addition & 1 deletion mm/huge_memory.c
Original file line number Diff line number Diff line change
Expand Up @@ -640,8 +640,8 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,

entry = mk_huge_pmd(page, vma->vm_page_prot);
entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
page_add_new_anon_rmap(page, vma, haddr, true);
mem_cgroup_commit_charge(page, memcg, false);
page_add_new_anon_rmap(page, vma, haddr, true);
lru_cache_add_active_or_unevictable(page, vma);
pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
Expand Down
2 changes: 1 addition & 1 deletion mm/khugepaged.c
Original file line number Diff line number Diff line change
Expand Up @@ -1175,8 +1175,8 @@ static void collapse_huge_page(struct mm_struct *mm,

spin_lock(pmd_ptl);
BUG_ON(!pmd_none(*pmd));
page_add_new_anon_rmap(new_page, vma, address, true);
mem_cgroup_commit_charge(new_page, memcg, false);
page_add_new_anon_rmap(new_page, vma, address, true);
count_memcg_events(memcg, THP_COLLAPSE_ALLOC, 1);
lru_cache_add_active_or_unevictable(new_page, vma);
pgtable_trans_huge_deposit(mm, pmd, pgtable);
Expand Down
27 changes: 9 additions & 18 deletions mm/memcontrol.c
Original file line number Diff line number Diff line change
Expand Up @@ -836,13 +836,6 @@ static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg,
struct page *page,
int nr_pages)
{
/*
* Here, RSS means 'mapped anon' and anon's SwapCache. Shmem/tmpfs is
* counted as CACHE even if it's on ANON LRU.
*/
if (PageAnon(page))
__mod_memcg_state(memcg, MEMCG_RSS, nr_pages);

if (abs(nr_pages) > 1) {
VM_BUG_ON_PAGE(!PageTransHuge(page), page);
__mod_memcg_state(memcg, MEMCG_RSS_HUGE, nr_pages);
Expand Down Expand Up @@ -1384,7 +1377,7 @@ static char *memory_stat_format(struct mem_cgroup *memcg)
*/

seq_buf_printf(&s, "anon %llu\n",
(u64)memcg_page_state(memcg, MEMCG_RSS) *
(u64)memcg_page_state(memcg, NR_ANON_MAPPED) *
PAGE_SIZE);
seq_buf_printf(&s, "file %llu\n",
(u64)memcg_page_state(memcg, NR_FILE_PAGES) *
Expand Down Expand Up @@ -3353,7 +3346,7 @@ static unsigned long mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)

if (mem_cgroup_is_root(memcg)) {
val = memcg_page_state(memcg, NR_FILE_PAGES) +
memcg_page_state(memcg, MEMCG_RSS);
memcg_page_state(memcg, NR_ANON_MAPPED);
if (swap)
val += memcg_page_state(memcg, MEMCG_SWAP);
} else {
Expand Down Expand Up @@ -3824,7 +3817,7 @@ static int memcg_numa_stat_show(struct seq_file *m, void *v)

static const unsigned int memcg1_stats[] = {
NR_FILE_PAGES,
MEMCG_RSS,
NR_ANON_MAPPED,
MEMCG_RSS_HUGE,
NR_SHMEM,
NR_FILE_MAPPED,
Expand Down Expand Up @@ -5455,7 +5448,12 @@ static int mem_cgroup_move_account(struct page *page,

lock_page_memcg(page);

if (!PageAnon(page)) {
if (PageAnon(page)) {
if (page_mapped(page)) {
__mod_lruvec_state(from_vec, NR_ANON_MAPPED, -nr_pages);
__mod_lruvec_state(to_vec, NR_ANON_MAPPED, nr_pages);
}
} else {
__mod_lruvec_state(from_vec, NR_FILE_PAGES, -nr_pages);
__mod_lruvec_state(to_vec, NR_FILE_PAGES, nr_pages);

Expand Down Expand Up @@ -6589,7 +6587,6 @@ void mem_cgroup_commit_charge(struct page *page, struct mem_cgroup *memcg,
{
unsigned int nr_pages = hpage_nr_pages(page);

VM_BUG_ON_PAGE(!page->mapping, page);
VM_BUG_ON_PAGE(PageLRU(page) && !lrucare, page);

if (mem_cgroup_disabled())
Expand Down Expand Up @@ -6662,8 +6659,6 @@ int mem_cgroup_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask,
struct mem_cgroup *memcg;
int ret;

VM_BUG_ON_PAGE(!page->mapping, page);

ret = mem_cgroup_try_charge(page, mm, gfp_mask, &memcg);
if (ret)
return ret;
Expand All @@ -6675,7 +6670,6 @@ struct uncharge_gather {
struct mem_cgroup *memcg;
unsigned long nr_pages;
unsigned long pgpgout;
unsigned long nr_anon;
unsigned long nr_kmem;
unsigned long nr_huge;
struct page *dummy_page;
Expand All @@ -6700,7 +6694,6 @@ static void uncharge_batch(const struct uncharge_gather *ug)
}

local_irq_save(flags);
__mod_memcg_state(ug->memcg, MEMCG_RSS, -ug->nr_anon);
__mod_memcg_state(ug->memcg, MEMCG_RSS_HUGE, -ug->nr_huge);
__count_memcg_events(ug->memcg, PGPGOUT, ug->pgpgout);
__this_cpu_add(ug->memcg->vmstats_percpu->nr_page_events, ug->nr_pages);
Expand Down Expand Up @@ -6740,8 +6733,6 @@ static void uncharge_page(struct page *page, struct uncharge_gather *ug)
if (!PageKmemcg(page)) {
if (PageTransHuge(page))
ug->nr_huge += nr_pages;
if (PageAnon(page))
ug->nr_anon += nr_pages;
ug->pgpgout++;
} else {
ug->nr_kmem += nr_pages;
Expand Down
10 changes: 5 additions & 5 deletions mm/memory.c
Original file line number Diff line number Diff line change
Expand Up @@ -2710,8 +2710,8 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
* thread doing COW.
*/
ptep_clear_flush_notify(vma, vmf->address, vmf->pte);
page_add_new_anon_rmap(new_page, vma, vmf->address, false);
mem_cgroup_commit_charge(new_page, memcg, false);
page_add_new_anon_rmap(new_page, vma, vmf->address, false);
lru_cache_add_active_or_unevictable(new_page, vma);
/*
* We call the notify macro here because, when using secondary
Expand Down Expand Up @@ -3243,12 +3243,12 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)

/* ksm created a completely new copy */
if (unlikely(page != swapcache && swapcache)) {
page_add_new_anon_rmap(page, vma, vmf->address, false);
mem_cgroup_commit_charge(page, memcg, false);
page_add_new_anon_rmap(page, vma, vmf->address, false);
lru_cache_add_active_or_unevictable(page, vma);
} else {
do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
mem_cgroup_commit_charge(page, memcg, true);
do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
activate_page(page);
}

Expand Down Expand Up @@ -3390,8 +3390,8 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
}

inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
page_add_new_anon_rmap(page, vma, vmf->address, false);
mem_cgroup_commit_charge(page, memcg, false);
page_add_new_anon_rmap(page, vma, vmf->address, false);
lru_cache_add_active_or_unevictable(page, vma);
setpte:
set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
Expand Down Expand Up @@ -3652,8 +3652,8 @@ vm_fault_t alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg,
/* copy-on-write page */
if (write && !(vma->vm_flags & VM_SHARED)) {
inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
page_add_new_anon_rmap(page, vma, vmf->address, false);
mem_cgroup_commit_charge(page, memcg, false);
page_add_new_anon_rmap(page, vma, vmf->address, false);
lru_cache_add_active_or_unevictable(page, vma);
} else {
inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
Expand Down
2 changes: 1 addition & 1 deletion mm/migrate.c
Original file line number Diff line number Diff line change
Expand Up @@ -2832,8 +2832,8 @@ static void migrate_vma_insert_page(struct migrate_vma *migrate,
goto unlock_abort;

inc_mm_counter(mm, MM_ANONPAGES);
page_add_new_anon_rmap(page, vma, addr, false);
mem_cgroup_commit_charge(page, memcg, false);
page_add_new_anon_rmap(page, vma, addr, false);
if (!is_zone_device_page(page))
lru_cache_add_active_or_unevictable(page, vma);
get_page(page);
Expand Down
47 changes: 29 additions & 18 deletions mm/rmap.c
Original file line number Diff line number Diff line change
Expand Up @@ -1114,6 +1114,11 @@ void do_page_add_anon_rmap(struct page *page,
bool compound = flags & RMAP_COMPOUND;
bool first;

if (unlikely(PageKsm(page)))
lock_page_memcg(page);
else
VM_BUG_ON_PAGE(!PageLocked(page), page);

if (compound) {
atomic_t *mapcount;
VM_BUG_ON_PAGE(!PageLocked(page), page);
Expand All @@ -1134,12 +1139,13 @@ void do_page_add_anon_rmap(struct page *page,
*/
if (compound)
__inc_node_page_state(page, NR_ANON_THPS);
__mod_node_page_state(page_pgdat(page), NR_ANON_MAPPED, nr);
__mod_lruvec_page_state(page, NR_ANON_MAPPED, nr);
}
if (unlikely(PageKsm(page)))
return;

VM_BUG_ON_PAGE(!PageLocked(page), page);
if (unlikely(PageKsm(page))) {
unlock_page_memcg(page);
return;
}

/* address might be in next vma when migration races vma_adjust */
if (first)
Expand Down Expand Up @@ -1181,7 +1187,7 @@ void page_add_new_anon_rmap(struct page *page,
/* increment count (starts at -1) */
atomic_set(&page->_mapcount, 0);
}
__mod_node_page_state(page_pgdat(page), NR_ANON_MAPPED, nr);
__mod_lruvec_page_state(page, NR_ANON_MAPPED, nr);
__page_set_anon_rmap(page, vma, address, 1);
}

Expand Down Expand Up @@ -1230,13 +1236,12 @@ static void page_remove_file_rmap(struct page *page, bool compound)
int i, nr = 1;

VM_BUG_ON_PAGE(compound && !PageHead(page), page);
lock_page_memcg(page);

/* Hugepages are not counted in NR_FILE_MAPPED for now. */
if (unlikely(PageHuge(page))) {
/* hugetlb pages are always mapped with pmds */
atomic_dec(compound_mapcount_ptr(page));
goto out;
return;
}

/* page still mapped by someone else? */
Expand All @@ -1246,14 +1251,14 @@ static void page_remove_file_rmap(struct page *page, bool compound)
nr++;
}
if (!atomic_add_negative(-1, compound_mapcount_ptr(page)))
goto out;
return;
if (PageSwapBacked(page))
__dec_node_page_state(page, NR_SHMEM_PMDMAPPED);
else
__dec_node_page_state(page, NR_FILE_PMDMAPPED);
} else {
if (!atomic_add_negative(-1, &page->_mapcount))
goto out;
return;
}

/*
Expand All @@ -1265,8 +1270,6 @@ static void page_remove_file_rmap(struct page *page, bool compound)

if (unlikely(PageMlocked(page)))
clear_page_mlock(page);
out:
unlock_page_memcg(page);
}

static void page_remove_anon_compound_rmap(struct page *page)
Expand Down Expand Up @@ -1310,7 +1313,7 @@ static void page_remove_anon_compound_rmap(struct page *page)
clear_page_mlock(page);

if (nr)
__mod_node_page_state(page_pgdat(page), NR_ANON_MAPPED, -nr);
__mod_lruvec_page_state(page, NR_ANON_MAPPED, -nr);
}

/**
Expand All @@ -1322,22 +1325,28 @@ static void page_remove_anon_compound_rmap(struct page *page)
*/
void page_remove_rmap(struct page *page, bool compound)
{
if (!PageAnon(page))
return page_remove_file_rmap(page, compound);
lock_page_memcg(page);

if (compound)
return page_remove_anon_compound_rmap(page);
if (!PageAnon(page)) {
page_remove_file_rmap(page, compound);
goto out;
}

if (compound) {
page_remove_anon_compound_rmap(page);
goto out;
}

/* page still mapped by someone else? */
if (!atomic_add_negative(-1, &page->_mapcount))
return;
goto out;

/*
* We use the irq-unsafe __{inc|mod}_zone_page_stat because
* these counters are not modified in interrupt context, and
* pte lock(a spinlock) is held, which implies preemption disabled.
*/
__dec_node_page_state(page, NR_ANON_MAPPED);
__dec_lruvec_page_state(page, NR_ANON_MAPPED);

if (unlikely(PageMlocked(page)))
clear_page_mlock(page);
Expand All @@ -1354,6 +1363,8 @@ void page_remove_rmap(struct page *page, bool compound)
* Leaving it set also helps swapoff to reinstate ptes
* faster for those pages still in swapcache.
*/
out:
unlock_page_memcg(page);
}

/*
Expand Down
4 changes: 2 additions & 2 deletions mm/swapfile.c
Original file line number Diff line number Diff line change
Expand Up @@ -1920,11 +1920,11 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
set_pte_at(vma->vm_mm, addr, pte,
pte_mkold(mk_pte(page, vma->vm_page_prot)));
if (page == swapcache) {
page_add_anon_rmap(page, vma, addr, false);
mem_cgroup_commit_charge(page, memcg, true);
page_add_anon_rmap(page, vma, addr, false);
} else { /* ksm created a completely new copy */
page_add_new_anon_rmap(page, vma, addr, false);
mem_cgroup_commit_charge(page, memcg, false);
page_add_new_anon_rmap(page, vma, addr, false);
lru_cache_add_active_or_unevictable(page, vma);
}
swap_free(entry);
Expand Down
2 changes: 1 addition & 1 deletion mm/userfaultfd.c
Original file line number Diff line number Diff line change
Expand Up @@ -123,8 +123,8 @@ static int mcopy_atomic_pte(struct mm_struct *dst_mm,
goto out_release_uncharge_unlock;

inc_mm_counter(dst_mm, MM_ANONPAGES);
page_add_new_anon_rmap(page, dst_vma, dst_addr, false);
mem_cgroup_commit_charge(page, memcg, false);
page_add_new_anon_rmap(page, dst_vma, dst_addr, false);
lru_cache_add_active_or_unevictable(page, dst_vma);

set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
Expand Down

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