On Tue, Oct 10, 2017 at 01:31:44PM -0700, Linus Torvalds wrote:
On Tue, Oct 10, 2017 at 12:44 PM, Andrew Morton
> This is all pretty mature code (isn't it?). Any idea why this bug
> popped up now?
I have no idea why it's suddenly popped up. It looks like it should
be a bohrbug, but it's actually a heisenbug, and I don't understand
Also, while the patch looks sane, the
line really threw me. That's an insane value to pick, it looks like
"bytes in page", but it isn't. It's just a random value that is bigger
than "PAGE_SIZE >> SECTOR_SHIFT".
I'd prefer to see just ~0u if the intention is just "bigger than
Actually, I did choose it to be "number of bytes in the page", based on
the reasoning that I didn't want to calculate what the actual block size
was, and the block size surely couldn't be any smaller than one byte. I
forgot about the SECTOR_SIZE limit on filesystem block size, so your
spelling of "big enough" does look better.
Now that I think about it some more, I suppose we might end up with a
situation where we're eventually passing a hugepage to this routine,
and futureproofing it with ~0U probably makes more sense.