On 10/22, Marco Elver wrote:
>
> On Tue, 22 Oct 2019 at 17:49, Oleg Nesterov wrote:
> >
> > Just for example. Suppose that task->state = TASK_UNINTERRUPTIBLE, this task
> > does __set_current_state(TASK_RUNNING), another CPU does
> > wake_up_process(task)
> &
On 10/17, Marco Elver wrote:
>
> + /*
> + * Delay this thread, to increase probability of observing a racy
> + * conflicting access.
> + */
> + udelay(get_delay());
> +
> + /*
> + * Re-read value, and check if it is as expected; if not, we infer a
> + * racy acc
d_held(),
> + RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(),
Yes, this is what I meant.
Sorry for confusion, I should have mentioned that rcu_sync_is_idle()
was recently updated when I suggested to use the new helper.
Acked-by: Oleg Nesterov
On 12/18, Roman Gushchin wrote:
>
> > > > > --- a/kernel/freezer.c
> > > > > +++ b/kernel/freezer.c
> > > > > @@ -134,7 +134,7 @@ bool freeze_task(struct task_struct *p)
> > > > > return false;
> > > > >
> > > > > spin_lock_irqsave(&freezer_lock, flags);
> > > > > - if
On 12/18, Roman Gushchin wrote:
>
> On Wed, Dec 12, 2018 at 06:49:02PM +0100, Oleg Nesterov wrote:
> > > > and btw what about suspend? try_to_freeze_tasks() will obviously
> > > > fail
> > > > if there is a ->frozen thread?
> > >
> >
On 12/11, Roman Gushchin wrote:
>
> On Tue, Dec 11, 2018 at 05:26:32PM +0100, Oleg Nesterov wrote:
> > On 12/07, Roman Gushchin wrote:
> > >
> > > Cgroup v2 freezer tries to put tasks into a state similar to jobctl
> > > stop. This means that tasks can be ki
On 12/07, Roman Gushchin wrote:
>
> Cgroup v2 freezer tries to put tasks into a state similar to jobctl
> stop. This means that tasks can be killed, ptraced (using
> PTRACE_SEIZE*), and interrupted. It is possible to attach to
> a frozen task, get some information (e.g. read registers) and detach.
On 11/30, Roman Gushchin wrote:
>
> void recalc_sigpending(void)
> {
> if (!recalc_sigpending_tsk(current) && !freezing(current) &&
> - !klp_patch_pending(current))
> + !klp_patch_pending(current) && !cgroup_task_frozen(current))
I must have missed something... but shouldn'
On 11/30, Roman Gushchin wrote:
>
> +void cgroup_enter_frozen(void)
> +{
> + if (!current->frozen) {
> + struct cgroup *cgrp;
> +
> + spin_lock_irq(&css_set_lock);
> + current->frozen = true;
> + cgrp = task_dfl_cgroup(current);
> + cg
To be honest, I fail to understand this patch. At least after a quick glance,
I will try to read it again tomorrow but so far I do not even understand the
desired semantics wrt signals/ptrace.
On 11/30, Roman Gushchin wrote:
>
> @@ -368,6 +369,8 @@ static inline int signal_pending_state(long state
Hi Ravi,
sorry for delay!
I am trying to recall what this code should do ;) At first glance, I do
not see any serious problem in this version... except it doesn't apply
to Linus's tree. just one question for now.
On 04/17, Ravi Bangoria wrote:
>
> @@ -941,6 +1091,9 @@ typedef bool (*filter_func_
Sorry Ravi, I saved the new version for review and forgot about it... I'll
try to do this on weekend.
On 05/03, Ravi Bangoria wrote:
>
> On 04/17/2018 10:02 AM, Ravi Bangoria wrote:
> > Userspace Statically Defined Tracepoints[1] are dtrace style markers
> > inside userspace applications. Applica
Hi Ravi,
On 04/10, Ravi Bangoria wrote:
>
> > and what if __mmu_notifier_register() fails simply because signal_pending()
> > == T?
> > see mm_take_all_locks().
> >
> > at first glance this all look suspicious and sub-optimal,
>
> Yes. I should have added checks for failure cases.
> Will fix them
On 04/04, Ravi Bangoria wrote:
>
> +static void sdt_add_mm_list(struct trace_uprobe *tu, struct mm_struct *mm)
> +{
> + struct mmu_notifier *mn;
> + struct sdt_mm_list *sml = kzalloc(sizeof(*sml), GFP_KERNEL);
> +
> + if (!sml)
> + return;
> + sml->mm = mm;
> + list_
On 04/04, Ravi Bangoria wrote:
>
> +static void sdt_add_mm_list(struct trace_uprobe *tu, struct mm_struct *mm)
> +{
> + struct mmu_notifier *mn;
> + struct sdt_mm_list *sml = kzalloc(sizeof(*sml), GFP_KERNEL);
> +
> + if (!sml)
> + return;
> + sml->mm = mm;
> + list_
On 03/19, Ravi Bangoria wrote:
>
> Hi Oleg,
>
> On 03/14/2018 10:29 PM, Oleg Nesterov wrote:
> > On 03/13, Ravi Bangoria wrote:
> >> +static bool sdt_valid_vma(struct trace_uprobe *tu, struct vm_area_struct
> >> *vma)
> >> +{
> >>
Hi Ravi,
On 03/19, Ravi Bangoria wrote:
>
> On 03/16/2018 11:20 PM, Oleg Nesterov wrote:
> >
> > And it seems that you are trying to confuse yourself, not only me ;) Just
> > suppose that an application does mmap+munmap in a loop and the mapped region
> > conta
On 03/16, Ravi Bangoria wrote:
>
> On 03/15/2018 08:19 PM, Oleg Nesterov wrote:
> > On 03/13, Ravi Bangoria wrote:
> >> For tiny binaries/libraries, different mmap regions points to the
> >> same file portion. In such cases, we may increment reference counte
On 03/15, Steven Rostedt wrote:
>
> On Tue, 13 Mar 2018 18:26:00 +0530
> Ravi Bangoria wrote:
>
> > +static void sdt_increment_ref_ctr(struct trace_uprobe *tu)
> > +{
> > + struct uprobe_map_info *info;
> > + struct vm_area_struct *vma;
> > + unsigned long vaddr;
> > +
> > + uprobe_start_d
On 03/16, Ravi Bangoria wrote:
>
> On 03/15/2018 08:00 PM, Oleg Nesterov wrote:
> > Note to mention that sdt_find_vma() can return NULL but the callers do
> > vma_offset_to_vaddr(vma) without any check.
>
> If the "mm" we are passing to sdt_find_vma() is r
On 03/13, Ravi Bangoria wrote:
>
> +sdt_update_ref_ctr(struct mm_struct *mm, unsigned long vaddr, short d)
> +{
> + void *kaddr;
> + struct page *page;
> + struct vm_area_struct *vma;
> + int ret = 0;
> + unsigned short orig = 0;
> +
> + if (vaddr == 0)
> + retur
On 03/13, Ravi Bangoria wrote:
>
> For tiny binaries/libraries, different mmap regions points to the
> same file portion. In such cases, we may increment reference counter
> multiple times.
Yes,
> But while de-registration, reference counter will get
> decremented only by once
could you explain
On 03/15, Oleg Nesterov wrote:
>
> > +static struct vm_area_struct *
> > +sdt_find_vma(struct mm_struct *mm, struct trace_uprobe *tu)
> > +{
> > + struct vm_area_struct *tmp;
> > +
> > + for (tmp = mm->mmap; tmp != NULL; tmp = tmp->vm_ne
On 03/13, Ravi Bangoria wrote:
>
> @@ -1053,6 +1056,9 @@ int uprobe_mmap(struct vm_area_struct *vma)
> struct uprobe *uprobe, *u;
> struct inode *inode;
>
> + if (uprobe_mmap_callback)
> + uprobe_mmap_callback(vma);
> +
> if (no_uprobe_events() || !valid_vma(vma, t
On 03/13, Ravi Bangoria wrote:
>
> +static bool sdt_valid_vma(struct trace_uprobe *tu, struct vm_area_struct
> *vma)
> +{
> + unsigned long vaddr = vma_offset_to_vaddr(vma, tu->ref_ctr_offset);
> +
> + return tu->ref_ctr_offset &&
> + vma->vm_file &&
> + file_inode(
On 09/05, robert.f...@collabora.com wrote:
>
> @@ -2854,6 +2854,7 @@ static const struct pid_entry tgid_base_stuff[] = {
> REG("clear_refs", S_IWUSR, proc_clear_refs_operations),
> REG("smaps", S_IRUGO, proc_pid_smaps_operations),
> REG("pagemap",S_IRUSR, proc_pagemap_ope
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