Messages in this thread |  | | | From | "Stephen C. Tweedie" <> | | Date | Thu, 15 Jul 1999 13:16:09 +0100 (BST) | | Subject | Re: [PATCH 2.2.10] Re: Problem with memmap file with SMP |
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Hi,
On Wed, 14 Jul 1999 14:52:46 -0700, Richard Henderson <rth@twiddle.net> said:
> On Wed, Jul 14, 1999 at 06:48:43PM +0100, Stephen C. Tweedie wrote: >> +{ >> + update_vm_cache_conditional(inode, pos, buf, count, 0); >> +}
> `0' isn't the best value to have chosen. Better something > like `-1' that can't be mapped in userspace.
0 is fine. The case we are trying to detect is an alias between the source buffer and the page cache, which is a kernel VA. 0 can never be mistaken for a valid kernel address, so it's just fine. Any user address would be OK --- it's only with kernel addresses that we'd have to be careful.
--Stephen
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