Messages in this thread | | | Date | Tue, 28 Apr 2015 09:57:11 -0700 | Subject | Re: Should mmap MAP_LOCKED fail if mm_poppulate fails? | From | Linus Torvalds <> |
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On Tue, Apr 28, 2015 at 9:43 AM, Michal Hocko <mhocko@suse.cz> wrote: > > Hmm, no other thread has the address from the current mmap call except > for MAP_FIXED (more on that below).
With things like opportunistic SIGSEGV handlers that map/unmap things as the user takes faults, that's actually not at all guaranteed.
Yeah, it's unusual, but I've seen it, with threaded applications where people play games with user-space memory management, and do "demand allocation" with mmap() in response to signals.
Admittedly we already do bad things in mmap(MAP_FIXED) for that case, since we dropped the vm lock. But at least it shouldn't be any worse than a thread speculatively touching the pages..
Linus
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