Messages in this thread |  | | Date | Wed, 19 Sep 2001 22:58:43 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: pre12 VM doubts and patch |
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On Thu, 20 Sep 2001, Andrea Arcangeli wrote: > > when the page is exclusive we definitely can write to it
NO!
If it is a read-only mapping, we must NOT mark it writable.
The fact is, the page may have been written to earlier, marked read-only with mprotect(), and the page is dirty but read-only, and swapping it in MUST NOT markt it writable even if it is our last exclusive copy.
Which we've gotten wrong for a long time, actually. But you #if 0'ed the fix that happened fairly recently.
Linus
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