Messages in this thread | | | Date | Mon, 23 Jul 2018 18:26:29 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH v6 3/6] Uprobes: Support SDT markers having reference count (semaphore) |
| |
I have a mixed feeling about this series... I'll try to summarise my thinking tomorrow, but I do not see any obvious problem so far. Although I have some concerns about 5/6, I need to re-read it after sleep.
On 07/16, Ravi Bangoria wrote: > > +static int delayed_uprobe_install(struct vm_area_struct *vma) > +{ > + struct list_head *pos, *q; > + struct delayed_uprobe *du; > + unsigned long vaddr; > + int ret = 0, err = 0; > + > + mutex_lock(&delayed_uprobe_lock); > + list_for_each_safe(pos, q, &delayed_uprobe_list) { > + du = list_entry(pos, struct delayed_uprobe, list); > + > + if (!du->uprobe->ref_ctr_offset ||
Is it possible to see ->ref_ctr_offset == 0 in delayed_uprobe_list?
> @@ -1072,7 +1282,13 @@ int uprobe_mmap(struct vm_area_struct *vma) > struct uprobe *uprobe, *u; > struct inode *inode; > > - if (no_uprobe_events() || !valid_vma(vma, true)) > + if (no_uprobe_events()) > + return 0; > + > + if (vma->vm_flags & VM_WRITE) > + delayed_uprobe_install(vma);
Obviously not nice performance-wise... OK, I do not know if it will actually hurt in practice and probably we can use the better data structures if necessary. But can't we check MMF_HAS_UPROBES at least? I mean,
if (vma->vm_flags & VM_WRITE && test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags)) delayed_uprobe_install(vma);
?
Perhaps we can even add another flag later, MMF_HAS_DELAYED_UPROBES set by delayed_uprobe_add().
Oleg.
| |