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proc/task_mmu: change proc_get_vma() to stop returning gate VMA at the end

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proc_get_vma() returning gate VMA at the end is desirable for the its
current m_start/m_next callers, as they need to report a gate VMA at the
end of the address space.  This behavior is very specific to these callers
and makes proc_get_vma() hard to use for other purposes.

Move this usage-specific behavior into the callers themselves so that
proc_get_vma() returns either a valid VMA, an error or a NULL when no more
VMAs are available.  This makes it more generic, simpler and usable in the
later patches.

Link: https://lore.kernel.org/20260918153318.758387-6-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Liam R. Howlett (Oracle) <liam@infradead.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Usama Arif <usama.arif@linux.dev>
Cc: Vlastimil Babka <vbabka@kernel.org>
This commit is contained in:
Suren Baghdasaryan 2026-09-18 08:33:16 -07:00 committed by Andrew Morton
parent a2432e2cfe
commit 60d21d883f
1 changed files with 23 additions and 5 deletions
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28
fs/proc/task_mmu.c
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@ -240,9 +240,6 @@ static struct vm_area_struct *proc_get_vma(struct seq_file *m, loff_t *ppos)
* found the extended vma with the same vm_start.
*/
*ppos = vma->vm_end;
} else {
*ppos = SENTINEL_VMA_GATE;
vma = get_gate_vma(priv->lock_ctx.mm);
}
return vma;
@ -252,6 +249,7 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
{
struct proc_maps_private *priv = m->private;
struct proc_maps_locking_ctx *lock_ctx;
struct vm_area_struct *vma;
loff_t last_addr = *ppos;
struct mm_struct *mm;
@ -281,19 +279,39 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
*ppos = last_addr = priv->last_pos;
vma_iter_init(&priv->iter, mm, (unsigned long)last_addr);
hold_task_mempolicy(priv);
/*
* If seq_file had to flush its collected data right after m_next() set
* position to SENTINEL_VMA_GATE, m_start() will get that sentinel and
* should return gate_vma without calling proc_get_vma().
*/
if (last_addr == SENTINEL_VMA_GATE)
return get_gate_vma(mm);
return proc_get_vma(m, ppos);
vma = proc_get_vma(m, ppos);
if (vma)
return vma;
/* Return gate VMA at the end */
*ppos = SENTINEL_VMA_GATE;
return get_gate_vma(mm);
}
static void *m_next(struct seq_file *m, void *v, loff_t *ppos)
{
struct proc_maps_private *priv = m->private;
struct vm_area_struct *vma;
if (*ppos == SENTINEL_VMA_GATE) {
*ppos = SENTINEL_VMA_END;
return NULL;
}
return proc_get_vma(m, ppos);
vma = proc_get_vma(m, ppos);
if (vma)
return vma;
/* Return gate VMA at the end */
*ppos = SENTINEL_VMA_GATE;
return get_gate_vma(priv->lock_ctx.mm);
}
static void m_stop(struct seq_file *m, void *v)