On Sat, Feb 27, 2021 at 01:11:35AM +0900, OGAWA Hirofumi wrote:
> zero_user_segments() is used from __block_write_begin_int(), for
> example like the following
>
> zero_user_segments(page, 4096, 1024, 512, 918)
>
> But new zero_user_segments() implements for HIGMEM + TRANSPARENT_HUGEPAGE
> doesn't handle "start > end" case correctly, and hits BUG_ON(). (we
> can fix __block_write_begin_int() instead though, it is the old and
> multiple usage)
Why don't we just take out the BUG_ON instead? The function doesn't
actually do the wrong thing.
> Also it calls kmap_atomic() unnecessary while start == end == 0.
I'm OK with that. It always used to do that.
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
Fixes: 0060ef3b4e6d ("mm: support THPs in zero_user_segments")
