A user with i386 instead of AMD64 machine reports [1] that commit 19809c2da28a
("mm, vmalloc: use __GFP_HIGHMEM implicitly”) causes a regression.
BUG_ON(PageHighMem(pg)) in drivers/media/common/saa7146/saa7146_core.c always
gets triggered after that commit.
Commit 704b862f9efd ("mm/vmalloc.c: don't unconditonally use __GFP_HIGHMEM”)
adjusts the mask logic, now the __GFP_HIGHMEM only gets applied when there is
no GFP_DMA or GFP_DMA32.
So I tried to adjust its malloc to "__vmalloc(nr_pages * sizeof(struct
scatterlist), GFP_KERNEL | GFP_DMA | __GFP_ZERO, PAGE_KERNEL)”, but both
GFP_DMA or GFP_DMA32 still trigger the BUG_ON(PageHighMem()) macro.
Also there are other BUG_ON(PageHighMem()) in drivers/media, I think they will
get hit by same regression in 32bit machine too.
[1] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1742316
Kai-Heng
