Back in 2.6 era, last_addr used to be stored in seq_file->version
variable, which was unsigned long. As a result, sentinels to represent
gate vma and end of all vmas used unsigned values. In more recent
kernels we don't used seq_file->version anymore and therefore conversion
from loff_t into unsigned type is not needed. Similarly, sentinel values
don't need to be unsigned. Remove type conversion for set_file position
and change sentinel values to signed.
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
fs/proc/task_mmu.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 751479eb128f..b8bc06d05a72 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -135,7 +135,7 @@ static struct vm_area_struct *proc_get_vma(struct proc_maps_private *priv,
if (vma) {
*ppos = vma->vm_start;
} else {
- *ppos = -2UL;
+ *ppos = -2;
vma = get_gate_vma(priv->mm);
}
@@ -145,11 +145,11 @@ static struct vm_area_struct *proc_get_vma(struct proc_maps_private *priv,
static void *m_start(struct seq_file *m, loff_t *ppos)
{
struct proc_maps_private *priv = m->private;
- unsigned long last_addr = *ppos;
+ loff_t last_addr = *ppos;
struct mm_struct *mm;
/* See m_next(). Zero at the start or after lseek. */
- if (last_addr == -1UL)
+ if (last_addr == -1)
return NULL;
priv->task = get_proc_task(priv->inode);
@@ -170,9 +170,9 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
return ERR_PTR(-EINTR);
}
- vma_iter_init(&priv->iter, mm, last_addr);
+ vma_iter_init(&priv->iter, mm, (unsigned long)last_addr);
hold_task_mempolicy(priv);
- if (last_addr == -2UL)
+ if (last_addr == -2)
return get_gate_vma(mm);
return proc_get_vma(priv, ppos);
@@ -180,8 +180,8 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
static void *m_next(struct seq_file *m, void *v, loff_t *ppos)
{
- if (*ppos == -2UL) {
- *ppos = -1UL;
+ if (*ppos == -2) {
+ *ppos = -1;
return NULL;
}
return proc_get_vma(m->private, ppos);
--
2.50.0.727.gbf7dc18ff4-googOn 7/4/25 08:07, Suren Baghdasaryan wrote:
> Back in 2.6 era, last_addr used to be stored in seq_file->version
> variable, which was unsigned long. As a result, sentinels to represent
> gate vma and end of all vmas used unsigned values. In more recent
> kernels we don't used seq_file->version anymore and therefore conversion
> from loff_t into unsigned type is not needed. Similarly, sentinel values
> don't need to be unsigned. Remove type conversion for set_file position
> and change sentinel values to signed.
>
> Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Some stuff in the code gave me a pause but it's out of scope here so just in
case someone wants to do some extra churn...
> ---
> fs/proc/task_mmu.c | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 751479eb128f..b8bc06d05a72 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -135,7 +135,7 @@ static struct vm_area_struct *proc_get_vma(struct proc_maps_private *priv,
> if (vma) {
> *ppos = vma->vm_start;
> } else {
> - *ppos = -2UL;
> + *ppos = -2;
> vma = get_gate_vma(priv->mm);
> }
>
> @@ -145,11 +145,11 @@ static struct vm_area_struct *proc_get_vma(struct proc_maps_private *priv,
> static void *m_start(struct seq_file *m, loff_t *ppos)
> {
> struct proc_maps_private *priv = m->private;
> - unsigned long last_addr = *ppos;
> + loff_t last_addr = *ppos;
> struct mm_struct *mm;
>
> /* See m_next(). Zero at the start or after lseek. */
> - if (last_addr == -1UL)
> + if (last_addr == -1)
> return NULL;
>
> priv->task = get_proc_task(priv->inode);
> @@ -170,9 +170,9 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
> return ERR_PTR(-EINTR);
> }
>
> - vma_iter_init(&priv->iter, mm, last_addr);
> + vma_iter_init(&priv->iter, mm, (unsigned long)last_addr);
I wonder if this should rather be done only after dealing with the -2 case
below. It seems wrong to init the iterator with a bogus address. What if it
acquires some sanity checks?
> hold_task_mempolicy(priv);
It seems suboptimal to do that mempolicy refcount dance for numa_maps sake
even if we're reading a different /proc file... maybe priv could have a flag
to determine?
> - if (last_addr == -2UL)
> + if (last_addr == -2)
> return get_gate_vma(mm);
I think only after the above it makes sense to init the iterator?
> return proc_get_vma(priv, ppos);
> @@ -180,8 +180,8 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
>
> static void *m_next(struct seq_file *m, void *v, loff_t *ppos)
> {
> - if (*ppos == -2UL) {
> - *ppos = -1UL;
> + if (*ppos == -2) {
> + *ppos = -1;
> return NULL;
> }
> return proc_get_vma(m->private, ppos);
On Tue, Jul 8, 2025 at 10:37 AM Vlastimil Babka <vbabka@suse.cz> wrote:
>
> On 7/4/25 08:07, Suren Baghdasaryan wrote:
> > Back in 2.6 era, last_addr used to be stored in seq_file->version
> > variable, which was unsigned long. As a result, sentinels to represent
> > gate vma and end of all vmas used unsigned values. In more recent
> > kernels we don't used seq_file->version anymore and therefore conversion
> > from loff_t into unsigned type is not needed. Similarly, sentinel values
> > don't need to be unsigned. Remove type conversion for set_file position
> > and change sentinel values to signed.
> >
> > Signed-off-by: Suren Baghdasaryan <surenb@google.com>
>
> Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
>
> Some stuff in the code gave me a pause but it's out of scope here so just in
> case someone wants to do some extra churn...
>
> > ---
> > fs/proc/task_mmu.c | 14 +++++++-------
> > 1 file changed, 7 insertions(+), 7 deletions(-)
> >
> > diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> > index 751479eb128f..b8bc06d05a72 100644
> > --- a/fs/proc/task_mmu.c
> > +++ b/fs/proc/task_mmu.c
> > @@ -135,7 +135,7 @@ static struct vm_area_struct *proc_get_vma(struct proc_maps_private *priv,
> > if (vma) {
> > *ppos = vma->vm_start;
> > } else {
> > - *ppos = -2UL;
> > + *ppos = -2;
> > vma = get_gate_vma(priv->mm);
> > }
> >
> > @@ -145,11 +145,11 @@ static struct vm_area_struct *proc_get_vma(struct proc_maps_private *priv,
> > static void *m_start(struct seq_file *m, loff_t *ppos)
> > {
> > struct proc_maps_private *priv = m->private;
> > - unsigned long last_addr = *ppos;
> > + loff_t last_addr = *ppos;
> > struct mm_struct *mm;
> >
> > /* See m_next(). Zero at the start or after lseek. */
> > - if (last_addr == -1UL)
> > + if (last_addr == -1)
> > return NULL;
> >
> > priv->task = get_proc_task(priv->inode);
> > @@ -170,9 +170,9 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
> > return ERR_PTR(-EINTR);
> > }
> >
> > - vma_iter_init(&priv->iter, mm, last_addr);
> > + vma_iter_init(&priv->iter, mm, (unsigned long)last_addr);
>
> I wonder if this should rather be done only after dealing with the -2 case
> below. It seems wrong to init the iterator with a bogus address. What if it
> acquires some sanity checks?
>
> > hold_task_mempolicy(priv);
>
> It seems suboptimal to do that mempolicy refcount dance for numa_maps sake
> even if we're reading a different /proc file... maybe priv could have a flag
> to determine?
>
> > - if (last_addr == -2UL)
> > + if (last_addr == -2)
> > return get_gate_vma(mm);
>
> I think only after the above it makes sense to init the iterator?
Yes makes sense but let me do that outside of this patchset as it's
rather unrelated.
>
> > return proc_get_vma(priv, ppos);
> > @@ -180,8 +180,8 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
> >
> > static void *m_next(struct seq_file *m, void *v, loff_t *ppos)
> > {
> > - if (*ppos == -2UL) {
> > - *ppos = -1UL;
> > + if (*ppos == -2) {
> > + *ppos = -1;
> > return NULL;
> > }
> > return proc_get_vma(m->private, ppos);
>
On Thu, Jul 03, 2025 at 11:07:24PM -0700, Suren Baghdasaryan wrote:
> Back in 2.6 era, last_addr used to be stored in seq_file->version
> variable, which was unsigned long. As a result, sentinels to represent
> gate vma and end of all vmas used unsigned values. In more recent
> kernels we don't used seq_file->version anymore and therefore conversion
> from loff_t into unsigned type is not needed. Similarly, sentinel values
> don't need to be unsigned. Remove type conversion for set_file position
> and change sentinel values to signed.
>
> Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Nice spot!
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> ---
> fs/proc/task_mmu.c | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 751479eb128f..b8bc06d05a72 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -135,7 +135,7 @@ static struct vm_area_struct *proc_get_vma(struct proc_maps_private *priv,
> if (vma) {
> *ppos = vma->vm_start;
> } else {
> - *ppos = -2UL;
> + *ppos = -2;
> vma = get_gate_vma(priv->mm);
> }
>
> @@ -145,11 +145,11 @@ static struct vm_area_struct *proc_get_vma(struct proc_maps_private *priv,
> static void *m_start(struct seq_file *m, loff_t *ppos)
> {
> struct proc_maps_private *priv = m->private;
> - unsigned long last_addr = *ppos;
> + loff_t last_addr = *ppos;
> struct mm_struct *mm;
>
> /* See m_next(). Zero at the start or after lseek. */
> - if (last_addr == -1UL)
> + if (last_addr == -1)
> return NULL;
>
> priv->task = get_proc_task(priv->inode);
> @@ -170,9 +170,9 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
> return ERR_PTR(-EINTR);
> }
>
> - vma_iter_init(&priv->iter, mm, last_addr);
> + vma_iter_init(&priv->iter, mm, (unsigned long)last_addr);
> hold_task_mempolicy(priv);
> - if (last_addr == -2UL)
> + if (last_addr == -2)
> return get_gate_vma(mm);
>
> return proc_get_vma(priv, ppos);
> @@ -180,8 +180,8 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
>
> static void *m_next(struct seq_file *m, void *v, loff_t *ppos)
> {
> - if (*ppos == -2UL) {
> - *ppos = -1UL;
> + if (*ppos == -2) {
> + *ppos = -1;
> return NULL;
> }
> return proc_get_vma(m->private, ppos);
> --
> 2.50.0.727.gbf7dc18ff4-goog
>
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