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SubjectRe: [PATCH] copy_from_high_bh
On Sun, 8 Jul 2001, Linus Torvalds wrote:
> On Sun, 8 Jul 2001 wrote:
> >
> > mm/highmem.c/copy_from_high_bh() blocks interrupts while copying "down"
> > to a bounce buffer, for writing.
> > This function is only ever called from create_bounce() (which cannot
> > be called from an interrupt context - it may block), and the kmap
> > 'KM_BOUNCE_WRITE' is only used in copy_from_high_bh().
> If so it's not just the interrupt disable that is unnecessary, the
> "kmap_atomic()" should also be just a plain "kmap()", I think.

That might eat through kmap()'s virtual window too quickly.

I did think about adding a test to see if the page was already mapped,
and falling back to kmap_atomic() if it isn't. That should give the best
of both worlds?


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