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    SubjectRe: [RFC 0/6] uprobes: kill uprobes_srcu/uprobe_srcu_id
    I'll write another email tomorrow, just one note...

    On 04/15, Peter Zijlstra wrote:
    >
    > OK, still not seeing how your proposal could work.. consider the below
    > patch comment, I'm not seeing how is_swbp_at_addr_fast() deals with an
    > in-progress INT3 while we remove the probe.
    >
    > By ensuring the non-race with reg/unreg it will either find the uprobe
    > (no problem)

    Yes,

    > or not find it and not see a breakpoint instruction either,
    > even though the pending breakpoint was generated by a uprobe (which is
    > now gone),

    Yes,

    > causing a false positive SIGTRAP.

    No. Please note that if is_swbp_at_addr_fast() sets is_swbp == 0 we
    restart this insn.

    (note that we also restart if get_user_pages() fails, this is hopefully
    is more correct too but minor).

    > Or am I still not getting it?

    My experience shows this is very unlikely. I am starting to think
    I missed something, will re-check.


    And. I have another reason for down_write() in register/unregister.
    I am still not sure this is possible (I had no time to try to
    implement), but it seems to me we can kill the uprobe counter in
    mm_struct.

    Oleg.



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