On Mon, May 04, 2020 at 02:35:09AM +0100, Al Viro wrote: > On Sun, May 03, 2020 at 06:09:01PM -0700, ira.weiny@xxxxxxxxx wrote: > > From: Ira Weiny <ira.weiny@xxxxxxxxx> > > > > The kmap infrastructure has been copied almost verbatim to every architecture. > > This series consolidates obvious duplicated code by defining core functions > > which call into the architectures only when needed. > > > > Some of the k[un]map_atomic() implementations have some similarities but the > > similarities were not sufficient to warrant further changes. > > > > In addition we remove a duplicate implementation of kmap() in DRM. > > > > Testing was done by 0day to cover all the architectures I can't readily > > build/test. > > OK... Looking through my old notes on kmap unification (this winter, never > went anywhere), > > * arch/mips/mm/cache.c ought to use linux/highmem.h, not asm/highmem.h > I suspect that your series doesn't build on some configs there. Hadn't > verified that, though. Yes patch 6 makes the change because kmap_atomic() was no longer declared in asm/highmem.h. I'm pretty sure 0-day caught that ... but I seem to remember noticing some oddness in that file and I did go through it by hand. > > * kmap_atomic_to_page() is dead, but not quite gone - csky and nds32 brought > the damn thing back (nds32 - only an extern). It needs killin'... Easy enough. Added as a follow on patch. > > * parisc is (arguably) abusing kunmap()/kunmap_atomic() for cache flushing. > Replace the bulk of its highmem.h with > #define ARCH_HAS_FLUSH_ON_KUNMAP > #define arch_before_kunmap flush_kernel_dcache_page_addr > and have default kunmap()/kunmap_atomic() do > #ifdef ARCH_HAS_FLUSH_ON_KUNMAP > arch_before_kunmap(page_address(page)); > #endif > and > #ifdef ARCH_HAS_FLUSH_ON_KUNMAP > arch_before_kunmap(addr); > #endif > resp. Kills ARCH_HAS_KMAP along with ifdefs on it, makes parisc use somewhat > less hacky. Agreed. Done in a follow on patch. > > I'd suggest checking various configs on mips - that's likely to cause headache. > Said that, my analysis of include chains back then is pretty much worthless > by now - I really hate the amount of indirect include chains leading to that > sucker on some, but not all configs ;-/ IIRC, the proof that everything > using kmap*/kunmap* would pull linux/highmem.h regardless of config took several > hours of digging, ran for several pages and had been hopelessly brittle. > arch/mips/mm/cache.c was the only exception caught by it, but these days > there might be more. Grepping for 'asm/highmem.h' and investigations don't reveal any issues... But you do have me worried. That said 0-day has been crunching on multiple versions of this series without issues such as this (save the mips issue above). I have to say it would be nice if the relation between linux/highmem.h and asm/highmem.h was more straightforward. Ira
