diff options
| author | Ingo Molnar <mingo@kernel.org> | 2017-04-23 11:37:17 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2017-04-23 11:45:20 +0200 |
| commit | 6dd29b3df975582ef429b5b93c899e6575785940 (patch) | |
| tree | f7f214935c45eb7ea9096fccd4cdace3baa99e68 /arch/powerpc | |
| parent | ace2fb5a8b65d6aba530068ea9331f18e10ef565 (diff) | |
Revert "x86/mm/gup: Switch GUP to the generic get_user_page_fast() implementation"
This reverts commit 2947ba054a4dabbd82848728d765346886050029.
Dan Williams reported dax-pmem kernel warnings with the following signature:
WARNING: CPU: 8 PID: 245 at lib/percpu-refcount.c:155 percpu_ref_switch_to_atomic_rcu+0x1f5/0x200
percpu ref (dax_pmem_percpu_release [dax_pmem]) <= 0 (0) after switching to atomic
... and bisected it to this commit, which suggests possible memory corruption
caused by the x86 fast-GUP conversion.
He also pointed out:
"
This is similar to the backtrace when we were not properly handling
pud faults and was fixed with this commit: 220ced1676c4 "mm: fix
get_user_pages() vs device-dax pud mappings"
I've found some missing _devmap checks in the generic
get_user_pages_fast() path, but this does not fix the regression
[...]
"
So given that there are known bugs, and a pretty robust looking bisection
points to this commit suggesting that are unknown bugs in the conversion
as well, revert it for the time being - we'll re-try in v4.13.
Reported-by: Dan Williams <dan.j.williams@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: aneesh.kumar@linux.vnet.ibm.com
Cc: dann.frazier@canonical.com
Cc: dave.hansen@intel.com
Cc: steve.capper@linaro.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/Kconfig | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 3a716b2dcde9..97a8bc8a095c 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -135,7 +135,7 @@ config PPC select HAVE_FUNCTION_GRAPH_TRACER select HAVE_FUNCTION_TRACER select HAVE_GCC_PLUGINS - select HAVE_GENERIC_GUP + select HAVE_GENERIC_RCU_GUP select HAVE_HW_BREAKPOINT if PERF_EVENTS && (PPC_BOOK3S || PPC_8xx) select HAVE_IDE select HAVE_IOREMAP_PROT |