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Date: Tue, 1 Jul 2014 15:02:01 +0200
From: "Jerome Marchand" <jmarchan@...hat.com>
To: linux-mm@...ck.org
Cc: linux-kernel@...r.kernel.org, Hugh Dickins <hughd@...gle.com>
Subject: [PATCH 5/5] mm, shmem: Show location of non-resident shmem pages in smaps
Adds ShmOther, ShmOrphan, ShmSwapCache and ShmSwap lines to
/proc/<pid>/smaps for shmem mappings.
ShmOther: amount of memory that is currently resident in memory, not
present in the page table of this process but present in the page
table of an other process.
ShmOrphan: amount of memory that is currently resident in memory but
not present in any process page table. This can happens when a process
unmaps a shared mapping it has accessed before or exits. Despite being
resident, this memory is not currently accounted to any process.
ShmSwapcache: amount of memory currently in swap cache
ShmSwap: amount of memory that is paged out on disk.
Signed-off-by: Jerome Marchand <jmarchan@...hat.com>
---
Documentation/filesystems/proc.txt | 11 ++++++++
fs/proc/task_mmu.c | 56 +++++++++++++++++++++++++++++++++++++-
2 files changed, 66 insertions(+), 1 deletion(-)
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index 1a15c56..a65ab59 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -422,6 +422,10 @@ Swap: 0 kB
KernelPageSize: 4 kB
MMUPageSize: 4 kB
Locked: 374 kB
+ShmOther: 124 kB
+ShmOrphan: 0 kB
+ShmSwapCache: 12 kB
+ShmSwap: 36 kB
VmFlags: rd ex mr mw me de
the first of these lines shows the same information as is displayed for the
@@ -437,6 +441,13 @@ a mapping associated with a file may contain anonymous pages: when MAP_PRIVATE
and a page is modified, the file page is replaced by a private anonymous copy.
"Swap" shows how much would-be-anonymous memory is also used, but out on
swap.
+The ShmXXX lines only appears for shmem mapping. They show the amount of memory
+from the mapping that is currently:
+ - resident in RAM, not present in the page table of this process but present
+ in the page table of an other process (ShmOther)
+ - resident in RAM but not present in the page table of any process (ShmOrphan)
+ - in swap cache (ShmSwapCache)
+ - paged out on swap (ShmSwap).
"VmFlags" field deserves a separate description. This member represents the kernel
flags associated with the particular virtual memory area in two letter encoded
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 73f0ce4..9b1de55 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -518,9 +518,33 @@ struct mem_size_stats {
unsigned long anonymous_thp;
unsigned long swap;
unsigned long nonlinear;
+ unsigned long shmem_resident_other;
+ unsigned long shmem_swapcache;
+ unsigned long shmem_swap;
+ unsigned long shmem_orphan;
u64 pss;
};
+void update_shmem_stats(struct mem_size_stats *mss, struct vm_area_struct *vma,
+ pgoff_t pgoff, unsigned long size)
+{
+ int count = 0;
+
+ switch (shmem_locate(vma, pgoff, &count)) {
+ case SHMEM_RESIDENT:
+ if (count)
+ mss->shmem_resident_other += size;
+ else
+ mss->shmem_orphan += size;
+ break;
+ case SHMEM_SWAPCACHE:
+ mss->shmem_swapcache += size;
+ break;
+ case SHMEM_SWAP:
+ mss->shmem_swap += size;
+ break;
+ }
+}
static void smaps_pte_entry(pte_t ptent, unsigned long addr,
unsigned long ptent_size, struct mm_walk *walk)
@@ -543,7 +567,8 @@ static void smaps_pte_entry(pte_t ptent, unsigned long addr,
} else if (pte_file(ptent)) {
if (pte_to_pgoff(ptent) != pgoff)
mss->nonlinear += ptent_size;
- }
+ } else if (pte_none(ptent) && shmem_vma(vma))
+ update_shmem_stats(mss, vma, pgoff, ptent_size);
if (!page)
return;
@@ -604,6 +629,21 @@ static int smaps_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
return 0;
}
+static int smaps_pte_hole(unsigned long addr, unsigned long end,
+ struct mm_walk *walk)
+{
+ struct mem_size_stats *mss = walk->private;
+ struct vm_area_struct *vma = mss->vma;
+ pgoff_t pgoff;
+
+ for (; addr != end; addr += PAGE_SIZE) {
+ pgoff = linear_page_index(vma, addr);
+ update_shmem_stats(mss, vma, pgoff, PAGE_SIZE);
+ }
+
+ return 0;
+}
+
static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma)
{
/*
@@ -670,6 +710,10 @@ static int show_smap(struct seq_file *m, void *v, int is_pid)
.private = &mss,
};
+ /* Only walk the holes when it'a a shmem mapping */
+ if (shmem_vma(vma))
+ smaps_walk.pte_hole = smaps_pte_hole;
+
memset(&mss, 0, sizeof mss);
mss.vma = vma;
/* mmap_sem is held in m_start */
@@ -712,6 +756,16 @@ static int show_smap(struct seq_file *m, void *v, int is_pid)
if (vma->vm_flags & VM_NONLINEAR)
seq_printf(m, "Nonlinear: %8lu kB\n",
mss.nonlinear >> 10);
+ if (shmem_vma(vma))
+ seq_printf(m,
+ "ShmOther: %8lu kB\n"
+ "ShmOrphan: %8lu kB\n"
+ "ShmSwapCache: %8lu kB\n"
+ "ShmSwap: %8lu kB\n",
+ mss.shmem_resident_other >> 10,
+ mss.shmem_orphan >> 10,
+ mss.shmem_swapcache >> 10,
+ mss.shmem_swap >> 10);
show_smap_vma_flags(m, vma);
--
1.9.3
--
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