The patch titled
Subject: fs/proc/task_mmu.c: kill the suboptimal and confusing m->version logic
has been added to the -mm tree. Its filename is
fs-proc-task_mmuc-kill-the-suboptimal-and-confusing-m-version-logic.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/fs-proc-task_mmuc-kill-the-suboptimal-and-confusing-m-version-logic.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/fs-proc-task_mmuc-kill-the-suboptimal-and-confusing-m-version-logic.patch
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------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: fs/proc/task_mmu.c: kill the suboptimal and confusing m->version logic
m_start() carefully documents, checks, and sets "m->version = -1" if
we are going to return NULL. The only problem is that we will be never
called again if m_start() returns NULL, so this is simply pointless
and misleading.
Otoh, ->show() methods m->version = 0 if vma == tail_vma and this is
just wrong, we want -1 in this case. And in fact we also want -1 if
->vm_next == NULL and ->tail_vma == NULL.
And it is not used consistently, the "scan vmas" loop in m_start()
should update last_addr too.
Finally, imo the whole "last_addr" logic in m_start() looks horrible.
find_vma(last_addr) is called unconditionally even if we are not going
to use the result. But the main problem is that this code participates
in tail_vma-or-NULL mess, and this looks simply unfixable.
Remove this optimization. We will add it back after some cleanups.
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 | 35 +----------------------------------
1 file changed, 1 insertion(+), 34 deletions(-)
diff -puN fs/proc/task_mmu.c~fs-proc-task_mmuc-kill-the-suboptimal-and-confusing-m-version-logic fs/proc/task_mmu.c
--- a/fs/proc/task_mmu.c~fs-proc-task_mmuc-kill-the-suboptimal-and-confusing-m-version-logic
+++ a/fs/proc/task_mmu.c
@@ -140,20 +140,10 @@ static void vma_stop(struct proc_maps_pr
static void *m_start(struct seq_file *m, loff_t *pos)
{
struct proc_maps_private *priv = m->private;
- unsigned long last_addr = m->version;
struct mm_struct *mm;
struct vm_area_struct *vma, *tail_vma = NULL;
loff_t l = *pos;
- /*
- * We remember last_addr rather than next_addr to hit with
- * vmacache most of the time. We have zero last_addr at
- * the beginning and also after lseek. We will have -1 last_addr
- * after the end of the vmas.
- */
- if (last_addr == -1UL)
- return NULL;
-
priv->task = get_pid_task(priv->pid, PIDTYPE_PID);
if (!priv->task)
return ERR_PTR(-ESRCH);
@@ -166,12 +156,6 @@ static void *m_start(struct seq_file *m,
tail_vma = get_gate_vma(mm);
priv->tail_vma = tail_vma;
hold_task_mempolicy(priv);
- /* Start with last addr hint */
- vma = find_vma(mm, last_addr);
- if (last_addr && vma) {
- vma = vma->vm_next;
- goto out;
- }
/*
* Check the vma index is within the range and do
@@ -192,8 +176,6 @@ out:
if (vma)
return vma;
- /* End of vmas has been reached */
- m->version = (tail_vma != NULL)? 0: -1UL;
if (tail_vma)
return tail_vma;
@@ -365,14 +347,7 @@ done:
static int show_map(struct seq_file *m, void *v, int is_pid)
{
- struct vm_area_struct *vma = v;
- struct proc_maps_private *priv = m->private;
-
- show_map_vma(m, vma, is_pid);
-
- if (m->count < m->size) /* vma is copied successfully */
- m->version = (vma != priv->tail_vma)
- ? vma->vm_start : 0;
+ show_map_vma(m, v, is_pid);
return 0;
}
@@ -598,7 +573,6 @@ static void show_smap_vma_flags(struct s
static int show_smap(struct seq_file *m, void *v, int is_pid)
{
- struct proc_maps_private *priv = m->private;
struct vm_area_struct *vma = v;
struct mem_size_stats mss;
struct mm_walk smaps_walk = {
@@ -651,10 +625,6 @@ static int show_smap(struct seq_file *m,
mss.nonlinear >> 10);
show_smap_vma_flags(m, vma);
-
- if (m->count < m->size) /* vma is copied successfully */
- m->version = (vma != priv->tail_vma)
- ? vma->vm_start : 0;
return 0;
}
@@ -1500,9 +1470,6 @@ static int show_numa_map(struct seq_file
seq_printf(m, " N%d=%lu", nid, md->node[nid]);
out:
seq_putc(m, '\n');
-
- if (m->count < m->size)
- m->version = (vma != proc_priv->tail_vma) ? vma->vm_start : 0;
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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