The patch titled
Subject: fs/proc/task_mmu.c: reintroduce m->version logic
has been removed from the -mm tree. Its filename was
fs-proc-task_mmuc-reintroduce-m-version-logic.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
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
@@ -146,13 +146,24 @@ 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);
@@ -165,6 +176,13 @@ 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;
@@ -340,6 +358,7 @@ 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;
}
@@ -617,6 +636,7 @@ static int show_smap(struct seq_file *m,
mss.nonlinear >> 10);
show_smap_vma_flags(m, vma);
+ m_cache_vma(m, vma);
return 0;
}
@@ -1471,6 +1491,7 @@ 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
signal-use-build_bug-instead-of-_nsig_words_is_unsupported_size.patch
signal-use-build_bug-instead-of-_nsig_words_is_unsupported_sizefix.patch
coredump-add-%i-%i-in-core_pattern-to-report-the-tid-of-the-crashed-thread.patch
ipc-shm-kill-the-historical-wrong-mm-start_stack-check.patch
linux-next.patch
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