Messages in this thread | | | Subject | Re: [PATCH] do_wp_page: BUG on invalid pfn | From | Ed L Cashin <> | Date | Fri, 15 Aug 2003 17:52:09 -0400 |
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Mike Fedyk <mfedyk@matchmail.com> writes:
> On Fri, Aug 15, 2003 at 05:15:45PM -0400, Ed L Cashin wrote: >> Rusty Russell <rusty@rustcorp.com.au> writes: >> >> > In message <87d6fixvpm.fsf@uga.edu> you write: >> >> This patch just does what the comment says should be done. >> > >> > Hi Ed! >> > >> > Not trivial I'm afraid. Send to Linus and lkml. >> >> >> This patch just does what the comment says should be done. I thought >> it was a trivial patch, but Rusty Russell has informed me otherwise. >> (Thanks, RR). >> >> >> --- linux-2.6.0-test2/mm/memory.c.orig Sun Jul 27 13:01:24 2003 >> +++ linux-2.6.0-test2/mm/memory.c Wed Aug 6 18:30:55 2003 >> @@ -990,15 +990,10 @@ >> int ret; >> >> if (unlikely(!pfn_valid(pfn))) { >> - /* >> - * This should really halt the system so it can be debugged or >> - * at least the kernel stops what it's doing before it corrupts >> - * data, but for the moment just pretend this is OOM. >> - */ >> - pte_unmap(page_table); >> printk(KERN_ERR "do_wp_page: bogus page at address %08lx\n", >> address); >> - goto oom; >> + dump_stack(); >> + BUG(); > > You're not unmapping the pte I guess to not interfere with the dump_stack,
This patch changes the logic from "pretend it's out of memory" to "announce something's very wrong and bail out right away." Unmapping the pte seems like a precursor to carrying on business as usual, but there must be some subtleties here that I am unaware of, or Rusty Russell wouldn't have called this patch non-trivial.
> but what about the printk? Will that affect the dump_stack also?
It seems like you'd return from the printk before dumping the stack, so I wouldn't think so.
-- --Ed L Cashin | PGP public key: ecashin@uga.edu | http://noserose.net/e/pgp/
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