From 60d21d883f071e69f363b6186201762c07aff548 Mon Sep 17 00:00:00 2001 From: Suren Baghdasaryan Date: Fri, 18 Sep 2026 08:33:16 -0700 Subject: [PATCH] proc/task_mmu: change proc_get_vma() to stop returning gate VMA at the end 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 Signed-off-by: Andrew Morton Reviewed-by: Lorenzo Stoakes (ARM) Acked-by: David Hildenbrand (Arm) Cc: Jann Horn Cc: Liam R. Howlett (Oracle) Cc: Matthew Wilcox (Oracle) Cc: "Paul E . McKenney" Cc: Pedro Falcato Cc: Usama Arif Cc: Vlastimil Babka --- fs/proc/task_mmu.c | 28 +++++++++++++++++++++++----- 1 file changed, 23 insertions(+), 5 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 06fa97241e9b..d075b715a80c 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -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)