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    SubjectRe: [PATCH v4 3.0-rc2-tip 13/22] 13: uprobes: Handing int3 and singlestep exception.
    > > +
    > > +cleanup_ret:
    > > + if (u) {
    > > + down_read(&mm->mmap_sem);
    > > + if (!set_orig_insn(current, u, probept, true))
    >
    > we try to undo the probe? That doesn't make any sense. I thought you
    > meant to return to userspace, let it re-take the trap and try again
    > until you do manage to allocate the user resource.

    I meant removing the probe itself
    https://lkml.org/lkml/2011/4/21/279

    We could try reseting and retrying the trap. Just that we might end up
    looping under memory pressure.

    >
    > This behaviour makes probes totally unreliable under memory pressure.

    Under memory pressure we could be unreliable.

    >
    > > + atomic_dec(&mm->uprobes_count);
    > > + up_read(&mm->mmap_sem);
    > > + put_uprobe(u);
    > > + } else {
    > > + /*TODO Return SIGTRAP signal */
    > > + }
    > > + if (utask) {
    > > + utask->active_uprobe = NULL;
    > > + utask->state = UTASK_RUNNING;
    > > + }
    > > + set_instruction_pointer(regs, probept);
    > > +}
    >
    > Also, there's a scary amount of TODO in there...

    All of those deal with delaying the signals. I am working on it at this
    moment.

    --
    Thanks and Regards
    Srikar


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