Messages in this thread | | | From | Linus Torvalds <> | Date | Sun, 20 Sep 2020 10:58:50 -0700 | Subject | Re: [patch RFC 00/15] mm/highmem: Provide a preemptible variant of kmap_atomic & friends |
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On Sun, Sep 20, 2020 at 10:42 AM Linus Torvalds <torvalds@linux-foundation.org> wrote: > > Yeah, that looks much easier to explain. Ack.
Btw, one thing that might be a good idea at least initially is to add a check for p->kmap_ctrl.idx being zero at fork, exit and maybe syscall return time (but that last one may be too cumbersome to really worry about).
The kmap_atomic() interface basically has a lot of coverage for leaked as part of all the "might_sleep()" checks sprinkled around, The new kmap_temporary/local/whatever wouldn't have that kind of incidental debug checking, and any leaked kmap indexes would be rather hard to debug (much) later when they cause index overflows or whatever.
Linus
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