Re: [PATCH] [13/16] HWPOISON: The high level memory error handler in the VM v3

Jens Axboe
2009-06-03T10:21:57Z

On Tue, Jun 02 2009, Wu Fengguang wrote:
> > And then this is possible because you aren't violating mm
> > assumptions due to 1b. This proceeds just as the existing
> > pagecache mce error handler case which exists now.
>
> Yeah that's a good scheme - we are talking about two interception
> scheme. Mine is passive one and yours is active one.
>
> passive: check hwpoison pages at __generic_make_request()/elv_next_request()
> (the code will be enabled by an mce_bad_io_pages counter)

That's not a feasible approach at all, it'll add O(N) scan of a bio at
queue time. Ditto for the elv_next_request() approach.

What would be cheaper is to check the pages at dma map time, since you
have to scan the request anyway. That means putting it in
blk_rq_map_sg() or similar.

--
Jens Axboe