The patch titled
Subject: fs/proc/task_mmu.c: reintroduce m->version logic
has been added to the -mm tree. Its filename is
fs-proc-task_mmuc-reintroduce-m-version-logic.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/fs-proc-task_mmuc-reintroduce-m-version-logic.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/fs-proc-task_mmuc-reintroduce-m-version-logic.patch
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The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: fs/proc/task_mmu.c: reintroduce m->version logic
Add the "last_addr" optimization back. Like before, every ->show()
method checks !seq_overflow() and sets m->version = vma->vm_start.
However, it also checks that m_next_vma(vma) != NULL, otherwise it
sets m->version = -1 for the lockless "EOF" fast-path in m_start().
m_start() can simply do find_vma() + m_next_vma() if last_addr is
not zero, the code looks clear and simple and this case is clearly
separated from "scan vmas" path.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/task_mmu.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff -puN fs/proc/task_mmu.c~fs-proc-task_mmuc-reintroduce-m-version-logic fs/proc/task_mmu.c
--- a/fs/proc/task_mmu.c~fs-proc-task_mmuc-reintroduce-m-version-logic
+++ a/fs/proc/task_mmu.c
@@ -145,13 +145,24 @@ m_next_vma(struct proc_maps_private *pri
return vma->vm_next ?: priv->tail_vma;
}
+static void m_cache_vma(struct seq_file *m, struct vm_area_struct *vma)
+{
+ if (m->count < m->size) /* vma is copied successfully */
+ m->version = m_next_vma(m->private, vma) ? vma->vm_start : -1UL;
+}
+
static void *m_start(struct seq_file *m, loff_t *ppos)
{
struct proc_maps_private *priv = m->private;
+ unsigned long last_addr = m->version;
struct mm_struct *mm;
struct vm_area_struct *vma;
unsigned int pos = *ppos;
+ /* See m_cache_vma(). Zero at the start or after lseek. */
+ if (last_addr == -1UL)
+ return NULL;
+
priv->task = get_pid_task(priv->pid, PIDTYPE_PID);
if (!priv->task)
return ERR_PTR(-ESRCH);
@@ -164,6 +175,13 @@ static void *m_start(struct seq_file *m,
hold_task_mempolicy(priv);
priv->tail_vma = get_gate_vma(mm);
+ if (last_addr) {
+ vma = find_vma(mm, last_addr);
+ if (vma && (vma = m_next_vma(priv, vma)))
+ return vma;
+ }
+
+ m->version = 0;
if (pos < mm->map_count) {
for (vma = mm->mmap; pos; pos--)
vma = vma->vm_next;
@@ -339,6 +357,7 @@ done:
static int show_map(struct seq_file *m, void *v, int is_pid)
{
show_map_vma(m, v, is_pid);
+ m_cache_vma(m, v);
return 0;
}
@@ -616,6 +635,7 @@ static int show_smap(struct seq_file *m,
mss.nonlinear >> 10);
show_smap_vma_flags(m, vma);
+ m_cache_vma(m, vma);
return 0;
}
@@ -1461,6 +1481,7 @@ static int show_numa_map(struct seq_file
seq_printf(m, " N%d=%lu", nid, md->node[nid]);
out:
seq_putc(m, '\n');
+ m_cache_vma(m, vma);
return 0;
}
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
earlyprintk-re-enable-earlyprintk-calling-early_param.patch
fs-proc-task_mmuc-dont-use-task-mm-in-m_start-and-show_map.patch
fs-proc-task_mmuc-unify-simplify-do_maps_open-and-numa_maps_open.patch
proc-introduce-proc_mem_open.patch
fs-proc-task_mmuc-shift-mm_access-from-m_start-to-proc_maps_open.patch
fs-proc-task_mmuc-simplify-the-vma_stop-logic.patch
fs-proc-task_mmuc-cleanup-the-tail_vma-horror-in-m_next.patch
fs-proc-task_mmuc-shift-priv-task-=-null-from-m_start-to-m_stop.patch
fs-proc-task_mmuc-kill-the-suboptimal-and-confusing-m-version-logic.patch
fs-proc-task_mmuc-simplify-m_start-to-make-it-readable.patch
fs-proc-task_mmuc-introduce-m_next_vma-helper.patch
fs-proc-task_mmuc-reintroduce-m-version-logic.patch
fs-proc-task_mmuc-update-m-version-in-the-main-loop-in-m_start.patch
fs-proc-task_nommuc-change-maps_open-to-use-__seq_open_private.patch
fs-proc-task_nommuc-shift-mm_access-from-m_start-to-proc_maps_open.patch
fs-proc-task_nommuc-dont-use-priv-task-mm.patch
linux-next.patch
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