Linus Torvalds 8e0d0ad206 sparc64: disable fast-GUP due to unexplained oopses ... HAVE_FAST_GUP enables the lockless quick page table walker for simple cases, and is a nice optimization for some random loads that can then use get_user_pages_fast() rather than the more careful page walker. However, for some unexplained reason, it seems to be subtly broken on sparc64. The breakage is only with some compiler versions and some hardware, and nobody seems to have figured out what triggers it, although there's a simple reprodicer for the problem when it does trigger. The problem was introduced with the conversion to the generic GUP code in commit 7b9afb86b6 ("sparc64: use the generic get_user_pages_fast code"), but nothing looks obviously wrong in that conversion. It may be a compiler bug that just hits us with the code reorganization. Or it may be something very specific to sparc64. This disables HAVE_FAST_GUP entirely. That makes things like futexes a bit slower, but at least they work. If we can figure out the trigger, that would be lovely, but it's been three months already.. Link: https://lore.kernel.org/lkml/20190717215956.GA30369@altlinux.org/ Fixes: 7b9afb86b6 ("sparc64: use the generic get_user_pages_fast code") Reported-by: Dmitry V Levin <ldv@altlinux.org> Reported-by: Anatoly Pugachev <matorola@gmail.com> Requested-by: Meelis Roos <mroos@linux.ee> Suggested-by: Christoph Hellwig <hch@infradead.org> Cc: David Miller <davem@davemloft.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2019-10-15 09:56:36 -07:00
..
boot	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 61	2019-05-24 17:36:45 +02:00
configs	sparc: configs: Remove useless UEVENT_HELPER_PATH	2019-06-13 14:12:19 -07:00
crypto	crypto: sparc/des - switch to new verification routines	2019-08-22 14:39:37 +10:00
include	arch/sparc/include/asm/pgtable_64.h: fix build	2019-09-26 10:27:06 -07:00
kernel	ipc: fix sparc64 ipc() wrapper	2019-09-07 21:42:25 +02:00
lib	sparc64: Add missing newline at end of file	2019-07-09 14:53:57 -07:00
math-emu	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00
mm	mm: treewide: clarify pgtable_page_{ctor,dtor}() naming	2019-09-26 10:10:44 -07:00
net	sparc: bpf: eliminate zero extension code-gen	2019-05-24 18:58:38 -07:00
oprofile	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00
power	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00
prom	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
vdso	kbuild: add --hash-style= and --build-id unconditionally	2019-07-17 22:37:51 +09:00
Kbuild	treewide: Add SPDX license identifier - Kbuild	2019-05-30 11:32:33 -07:00
Kconfig	sparc64: disable fast-GUP due to unexplained oopses	2019-10-15 09:56:36 -07:00
Kconfig.debug	Kconfig: consolidate the "Kernel hacking" menu	2018-08-02 08:06:48 +09:00
Makefile	sparc: generate uapi header and system call table files	2018-11-18 18:52:22 -08:00