Messages in this thread | | | Date | Fri, 15 Sep 2023 14:15:15 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH] proc: nommu: /proc/<pid>/maps: release mmap read lock |
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On 09/14, Ben Wolsieffer wrote: > > Fixes: 47fecca15c09 ("fs/proc/task_nommu.c: don't use priv->task->mm") > Signed-off-by: Ben Wolsieffer <ben.wolsieffer@hefring.com> > --- > fs/proc/task_nommu.c | 27 +++++++++++++++------------ > 1 file changed, 15 insertions(+), 12 deletions(-)
Acked-by: Oleg Nesterov <oleg@redhat.com>
------------------------------------------------------------------------------- Sorry for the offtopic question. I know NOTHING about nommu and when I tried to review this patch I was puzzled by
/* See m_next(). Zero at the start or after lseek. */ if (addr == -1UL) return NULL;
at the start of m_start(). OK, lets look at
static void *m_next(struct seq_file *m, void *_p, loff_t *pos) { struct vm_area_struct *vma = _p;
*pos = vma->vm_end; return find_vma(vma->vm_mm, vma->vm_end); }
where does this -1UL come from? Does this mean that on nommu
last_vma->vm_end == -1UL
or what?
fs/proc/task_mmu.c has the same check at the start, but in this case the "See m_next()" comment actually helps.
Just curious, thanks.
Oleg.
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