Re: [PATCH 06/33] readahead: refactor __do_page_cache_readahead()

[Paul Mackerras]

Andrew Morton writes:

> Wu Fengguang <wfg@xxxxxxxxxxxxxxxx> wrote:
> > @@ -302,6 +303,8 @@ __do_page_cache_readahead(struct address
> >  			break;
> >  		page->index = page_offset;
> >  		list_add(&page->lru, &page_pool);
> > +		if (page_idx == nr_to_read - lookahead_size)
> > +			__SetPageReadahead(page);
> >  		ret++;
> >  	}
> 
> OK.  But the __SetPageFoo() things still give me the creeps.

I just hope that Wu Fengguang, or whoever is making these patches,
realizes that on some architectures, doing __set_bit on one CPU
concurrently with another CPU doing set_bit on a different bit in the
same word can result in the second CPU's update getting lost...

Paul.
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