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SubjectTwo VM problems for the 2.4 TODO list
Hi Ted,

To be fixed for 2.4:

1) Non-atomic pte updates

The page aging code and mprotect both modify existing ptes
non-atomically. That can stomp on the VM hardware on other CPUs
setting the dirty bit on mmaped pages when using threads. 2.2 is
vulnerable too.

2) RSS locking

swapout holds the page_table_lock while swapping, and adjusts the
mm->rss while holding that lock. Other places in the mm are not
so careful about holding the lock, so rss (which is not an
atomic_t) can be corrupted.

--Stephen

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