Messages in this thread | | | Date | Sun, 4 Jul 1999 10:49:56 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: [patch] fix for OOM deadlock in swap_in (2.2.10) [Re: [test program] for OOM situations ] |
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On Sun, 4 Jul 1999, Andrea Arcangeli wrote: > > The first patch I sent you some time ago was buggy since I replaced the > sigbus with a sigkill in do_page_fault, but now I force the signals only > at the lower level (as shm and other places was just doing) and the retval > of handle_mm_fault now _only_ tells do_page_fault if it has to fixup or > not.
Ok. I still have your old patch, I'll just flush it so I don't confuse it with anything else.
However, I still much prefer the 2.3.x approach (ie just returning more than just 0/1 - a negative number means out-of-memory). In particular, your current approach gets the ptrace() case wrong for the SIGBUS case, and it's pretty much impossible to fix cleanly as far as I can tell.
Note that 2.3.10-pre2 also gets ptrace() wrong, but at least it's not impossible to fix - it should just bother to check the return value it gets from handle_mm_fault(). Right now it doesn't.
Note that ptrace() is a horrible special case, being the only thing that accesses another process VM space (apart from vmscan which is also horrible, in other ways). HOWEVER, it's rather bad to have a SIGBUS problem and then when you try to debug it the debugger also gets a SIGBUS, which is what your approach results in.
Linus
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