Re: 2.4.23pre6aa1

[Mike Fedyk <mfedyk@matchmail.com>]

On Thu, Oct 02, 2003 at 05:26:48PM +0200, Andrea Arcangeli wrote:
> Only in 2.4.23pre6aa1: 05_vm_27-pte-dirty-bit-in-hardware-1
> 
> 	This fixes a longstanding bug for a number of archs that haven't the
> 	dirty bit updated in hardware. For those archs we can't mark the pte
> 	writeable when it's still in swap cache, unless we don't mark it dirty
> 	too at the same time. Otherwise the cpu will go ahead writing to the
> 	page, no fault will happen and the swapcache will be still clean, and
> 	the data will be lost at the next zeroIO swapout leading to userspace
> 	data corruption and segfaults during swap. Affected archs are
> 	alpha/s390/s390x for example.
> 
> 	This bug was specific to the -aa VM, it couldn't happen
> 	in mainline. In my tree I optimized the code to exploited
> 	properties of archs that updates the bit in hardware for the
> 	first time. Hence the first need of a #define to differentiate the
> 	two code paths. The logic in the software-dirty-bit case will
> 	be less efficient of course (that's why there's a difference
> 	in the first place).

What does rmap do in this case then?