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. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>