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proc/task_mmu: remove special-casing of smap_gather_stats() start parameter

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smap_gather_stats() interprets its start parameter to mean vma->vm_start
when it's set to 0.  Eliminate this special interpretation and provide two
separate functions for a partial and complete VMA walk.

Since smap_gather_stats() operates within a single VMA, we can replace
walk_page_vma()/walk_page_range() calls with walk_page_range_vma() which
is simpler and also can be called while holding per-VMA lock.

No functional change intended.

Link: https://lore.kernel.org/20260918153318.758387-5-surenb@google.com
Suggested-by: Lorenzo Stoakes <ljs@kernel.org>
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 08:33:15 -07:00 committed by Andrew Morton
parent 66757cdd0b
commit a2432e2cfe
1 changed files with 35 additions and 17 deletions
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52
fs/proc/task_mmu.c
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@ -1250,20 +1250,26 @@ get_smaps_shmem_walk_ops(struct proc_maps_private *priv)
return &smaps_shmem_walk_vma_lock_ops;
}
/*
* Gather mem stats from @vma with the indicated beginning
* address @start, and keep them in @mss.
/**
* smap_gather_stats_range() - Gather mem stats from a portion of the @vma.
* @priv: proc maps private state.
* @vma: The VMA to gather stats for.
* @mss: The accumulated stats.
* @start: The address from which to start.
*
* Use vm_start of @vma as the beginning address if @start is 0.
* This gathers stats for the portion of the VMA starting at the @start
* address.
*/
static void smap_gather_stats(struct proc_maps_private *priv,
struct vm_area_struct *vma,
struct mem_size_stats *mss, unsigned long start)
static void smap_gather_stats_range(struct proc_maps_private *priv,
struct vm_area_struct *vma,
struct mem_size_stats *mss,
unsigned long start)
{
const struct mm_walk_ops *ops = get_smaps_walk_ops(priv);
const bool is_partial = start > vma->vm_start;
/* Invalid start */
if (start >= vma->vm_end)
if (start < vma->vm_start || start >= vma->vm_end)
return;
if (vma == get_gate_vma(priv->lock_ctx.mm))
@ -1282,20 +1288,31 @@ static void smap_gather_stats(struct proc_maps_private *priv,
const unsigned long shmem_swapped = shmem_swap_usage(vma);
const bool is_cow = vma_is_cow_mapping(vma);
if (start || (shmem_swapped && is_cow))
if (is_partial || (shmem_swapped && is_cow))
ops = get_smaps_shmem_walk_ops(priv);
else
mss->swap += shmem_swapped;
}
if (!start)
walk_page_vma(vma, ops, mss);
else
walk_page_range(vma->vm_mm, start, vma->vm_end, ops, mss);
walk_page_range_vma(vma, start, vma->vm_end, ops, mss);
reacquire_rcu(priv);
}
/**
* smap_gather_stats() - Gather mem stats from the entire @vma.
* @priv: proc maps private state.
* @vma: The VMA to gather stats for.
* @mss: The accumulated stats.
*
* This gathers stats for the whole of the VMA.
*/
static void smap_gather_stats(struct proc_maps_private *priv,
struct vm_area_struct *vma, struct mem_size_stats *mss)
{
smap_gather_stats_range(priv, vma, mss, vma->vm_start);
}
#define SEQ_PUT_DEC(str, val) \
seq_put_decimal_ull_width(m, str, (val) >> 10, 8)
@ -1346,7 +1363,7 @@ static int show_smap(struct seq_file *m, void *v)
struct vm_area_struct *vma = v;
struct mem_size_stats mss = {};
smap_gather_stats(priv, vma, &mss, 0);
smap_gather_stats(priv, vma, &mss);
show_map_vma(m, vma);
@ -1399,7 +1416,7 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
vma_start = vma->vm_start;
do {
smap_gather_stats(priv, vma, &mss, 0);
smap_gather_stats(priv, vma, &mss);
last_vma_end = vma->vm_end;
/*
@ -1458,14 +1475,15 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
/* Case 1 and 2 above */
if (vma->vm_start >= last_vma_end) {
smap_gather_stats(priv, vma, &mss, 0);
smap_gather_stats(priv, vma, &mss);
last_vma_end = vma->vm_end;
continue;
}
/* Case 4 above */
if (vma->vm_end > last_vma_end) {
smap_gather_stats(priv, vma, &mss, last_vma_end);
smap_gather_stats_range(priv, vma, &mss,
last_vma_end);
last_vma_end = vma->vm_end;
}
}