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Subject[PATCH v5 5/6] mm, shmem: add internal shmem resident memory accounting
Date
From: Jerome Marchand <jmarchan@redhat.com>

Currently looking at /proc/<pid>/status or statm, there is no way to
distinguish shmem pages from pages mapped to a regular file (shmem pages are
mapped to /dev/zero), even though their implication in actual memory use is
quite different.

The internal accounting currently counts shmem pages together with regular
files. As a preparation to extend the userspace interfaces, this patch adds
MM_SHMEMPAGES counter to mm_rss_stat to account for shmem pages separately from
MM_FILEPAGES. The next patch will expose it to userspace - this patch doesn't
change the exported values yet, by adding up MM_SHMEMPAGES to MM_FILEPAGES at
places where MM_FILEPAGES was used before. The only user-visible change after
this patch is the OOM killer message that separates the reported "shmem-rss"
from "file-rss".

[vbabka@suse.cz: forward-porting, tweak changelog]
Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hugh Dickins <hughd@google.com>
---
arch/s390/mm/pgtable.c | 5 +----
fs/proc/task_mmu.c | 3 ++-
include/linux/mm.h | 18 +++++++++++++++++-
include/linux/mm_types.h | 7 ++++---
kernel/events/uprobes.c | 2 +-
mm/memory.c | 30 ++++++++++--------------------
mm/oom_kill.c | 5 +++--
mm/rmap.c | 12 +++---------
8 files changed, 41 insertions(+), 41 deletions(-)

diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 34f3790..43b9a48 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -603,10 +603,7 @@ static void gmap_zap_swap_entry(swp_entry_t entry, struct mm_struct *mm)
else if (is_migration_entry(entry)) {
struct page *page = migration_entry_to_page(entry);

- if (PageAnon(page))
- dec_mm_counter(mm, MM_ANONPAGES);
- else
- dec_mm_counter(mm, MM_FILEPAGES);
+ dec_mm_counter(mm, mm_counter(page));
}
free_swap_and_cache(entry);
}
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index a0338ec..19d190b 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -83,7 +83,8 @@ unsigned long task_statm(struct mm_struct *mm,
unsigned long *shared, unsigned long *text,
unsigned long *data, unsigned long *resident)
{
- *shared = get_mm_counter(mm, MM_FILEPAGES);
+ *shared = get_mm_counter(mm, MM_FILEPAGES) +
+ get_mm_counter(mm, MM_SHMEMPAGES);
*text = (PAGE_ALIGN(mm->end_code) - (mm->start_code & PAGE_MASK))
>> PAGE_SHIFT;
*data = mm->total_vm - mm->shared_vm;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index fc9a3b8..25cdec3 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1342,10 +1342,26 @@ static inline void dec_mm_counter(struct mm_struct *mm, int member)
atomic_long_dec(&mm->rss_stat.count[member]);
}

+/* Optimized variant when page is already known not to be PageAnon */
+static inline int mm_counter_file(struct page *page)
+{
+ if (PageSwapBacked(page))
+ return MM_SHMEMPAGES;
+ return MM_FILEPAGES;
+}
+
+static inline int mm_counter(struct page *page)
+{
+ if (PageAnon(page))
+ return MM_ANONPAGES;
+ return mm_counter_file(page);
+}
+
static inline unsigned long get_mm_rss(struct mm_struct *mm)
{
return get_mm_counter(mm, MM_FILEPAGES) +
- get_mm_counter(mm, MM_ANONPAGES);
+ get_mm_counter(mm, MM_ANONPAGES) +
+ get_mm_counter(mm, MM_SHMEMPAGES);
}

static inline unsigned long get_mm_hiwater_rss(struct mm_struct *mm)
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 5e37e91..22beb22 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -361,9 +361,10 @@ struct core_state {
};

enum {
- MM_FILEPAGES,
- MM_ANONPAGES,
- MM_SWAPENTS,
+ MM_FILEPAGES, /* Resident file mapping pages */
+ MM_ANONPAGES, /* Resident anonymous pages */
+ MM_SWAPENTS, /* Anonymous swap entries */
+ MM_SHMEMPAGES, /* Resident shared memory pages */
NR_MM_COUNTERS
};

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 5137399..373a3ab 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -181,7 +181,7 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
lru_cache_add_active_or_unevictable(kpage, vma);

if (!PageAnon(page)) {
- dec_mm_counter(mm, MM_FILEPAGES);
+ dec_mm_counter(mm, mm_counter_file(page));
inc_mm_counter(mm, MM_ANONPAGES);
}

diff --git a/mm/memory.c b/mm/memory.c
index 7f3b9f2..f5b8e8c 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -826,10 +826,7 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
} else if (is_migration_entry(entry)) {
page = migration_entry_to_page(entry);

- if (PageAnon(page))
- rss[MM_ANONPAGES]++;
- else
- rss[MM_FILEPAGES]++;
+ rss[mm_counter(page)]++;

if (is_write_migration_entry(entry) &&
is_cow_mapping(vm_flags)) {
@@ -868,10 +865,7 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
if (page) {
get_page(page);
page_dup_rmap(page, false);
- if (PageAnon(page))
- rss[MM_ANONPAGES]++;
- else
- rss[MM_FILEPAGES]++;
+ rss[mm_counter(page)]++;
}

out_set_pte:
@@ -1107,9 +1101,8 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
tlb_remove_tlb_entry(tlb, pte, addr);
if (unlikely(!page))
continue;
- if (PageAnon(page))
- rss[MM_ANONPAGES]--;
- else {
+
+ if (!PageAnon(page)) {
if (pte_dirty(ptent)) {
force_flush = 1;
set_page_dirty(page);
@@ -1117,8 +1110,8 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
if (pte_young(ptent) &&
likely(!(vma->vm_flags & VM_SEQ_READ)))
mark_page_accessed(page);
- rss[MM_FILEPAGES]--;
}
+ rss[mm_counter(page)]--;
page_remove_rmap(page, false);
if (unlikely(page_mapcount(page) < 0))
print_bad_pte(vma, addr, ptent, page);
@@ -1140,11 +1133,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
struct page *page;

page = migration_entry_to_page(entry);
-
- if (PageAnon(page))
- rss[MM_ANONPAGES]--;
- else
- rss[MM_FILEPAGES]--;
+ rss[mm_counter(page)]--;
}
if (unlikely(!free_swap_and_cache(entry)))
print_bad_pte(vma, addr, ptent, NULL);
@@ -1454,7 +1443,7 @@ static int insert_page(struct vm_area_struct *vma, unsigned long addr,

/* Ok, finally just insert the thing.. */
get_page(page);
- inc_mm_counter_fast(mm, MM_FILEPAGES);
+ inc_mm_counter_fast(mm, mm_counter_file(page));
page_add_file_rmap(page);
set_pte_at(mm, addr, pte, mk_pte(page, prot));

@@ -2091,7 +2080,8 @@ static int wp_page_copy(struct mm_struct *mm, struct vm_area_struct *vma,
if (likely(pte_same(*page_table, orig_pte))) {
if (old_page) {
if (!PageAnon(old_page)) {
- dec_mm_counter_fast(mm, MM_FILEPAGES);
+ dec_mm_counter_fast(mm,
+ mm_counter_file(old_page));
inc_mm_counter_fast(mm, MM_ANONPAGES);
}
} else {
@@ -2815,7 +2805,7 @@ void do_set_pte(struct vm_area_struct *vma, unsigned long address,
inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
page_add_new_anon_rmap(page, vma, address, false);
} else {
- inc_mm_counter_fast(vma->vm_mm, MM_FILEPAGES);
+ inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
page_add_file_rmap(page);
}
set_pte_at(vma->vm_mm, address, pte, entry);
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index d13a339..5314b20 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -585,10 +585,11 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p,
*/
do_send_sig_info(SIGKILL, SEND_SIG_FORCED, victim, true);
mark_oom_victim(victim);
- pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB\n",
+ pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB\n",
task_pid_nr(victim), victim->comm, K(victim->mm->total_vm),
K(get_mm_counter(victim->mm, MM_ANONPAGES)),
- K(get_mm_counter(victim->mm, MM_FILEPAGES)));
+ K(get_mm_counter(victim->mm, MM_FILEPAGES)),
+ K(get_mm_counter(victim->mm, MM_SHMEMPAGES)));
task_unlock(victim);

/*
diff --git a/mm/rmap.c b/mm/rmap.c
index e045fea..2d87940 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1450,10 +1450,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
if (PageHuge(page)) {
hugetlb_count_sub(1 << compound_order(page), mm);
} else {
- if (PageAnon(page))
- dec_mm_counter(mm, MM_ANONPAGES);
- else
- dec_mm_counter(mm, MM_FILEPAGES);
+ dec_mm_counter(mm, mm_counter(page));
}
set_pte_at(mm, address, pte,
swp_entry_to_pte(make_hwpoison_entry(page)));
@@ -1463,10 +1460,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
* interest anymore. Simply discard the pte, vmscan
* will take care of the rest.
*/
- if (PageAnon(page))
- dec_mm_counter(mm, MM_ANONPAGES);
- else
- dec_mm_counter(mm, MM_FILEPAGES);
+ dec_mm_counter(mm, mm_counter(page));
} else if (IS_ENABLED(CONFIG_MIGRATION) && (flags & TTU_MIGRATION)) {
swp_entry_t entry;
pte_t swp_pte;
@@ -1506,7 +1500,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
swp_pte = pte_swp_mksoft_dirty(swp_pte);
set_pte_at(mm, address, pte, swp_pte);
} else
- dec_mm_counter(mm, MM_FILEPAGES);
+ dec_mm_counter(mm, mm_counter_file(page));

page_remove_rmap(page, PageHuge(page));
page_cache_release(page);
--
2.6.3


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