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authorIngo Molnar <mingo@kernel.org>2017-04-23 12:37:17 +0300
committerIngo Molnar <mingo@kernel.org>2017-04-23 12:45:20 +0300
commit6dd29b3df975582ef429b5b93c899e6575785940 (patch)
treef7f214935c45eb7ea9096fccd4cdace3baa99e68 /arch/x86/include/asm/pgtable.h
parentace2fb5a8b65d6aba530068ea9331f18e10ef565 (diff)
downloadlinux-6dd29b3df975582ef429b5b93c899e6575785940.tar.xz
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/x86/include/asm/pgtable.h')
-rw-r--r--arch/x86/include/asm/pgtable.h53
1 files changed, 0 insertions, 53 deletions
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 942482ac36a8..f5af95a0c6b8 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -244,11 +244,6 @@ static inline int pud_devmap(pud_t pud)
return 0;
}
#endif
-
-static inline int pgd_devmap(pgd_t pgd)
-{
- return 0;
-}
#endif
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
@@ -1190,54 +1185,6 @@ static inline u16 pte_flags_pkey(unsigned long pte_flags)
#endif
}
-static inline bool __pkru_allows_pkey(u16 pkey, bool write)
-{
- u32 pkru = read_pkru();
-
- if (!__pkru_allows_read(pkru, pkey))
- return false;
- if (write && !__pkru_allows_write(pkru, pkey))
- return false;
-
- return true;
-}
-
-/*
- * 'pteval' can come from a PTE, PMD or PUD. We only check
- * _PAGE_PRESENT, _PAGE_USER, and _PAGE_RW in here which are the
- * same value on all 3 types.
- */
-static inline bool __pte_access_permitted(unsigned long pteval, bool write)
-{
- unsigned long need_pte_bits = _PAGE_PRESENT|_PAGE_USER;
-
- if (write)
- need_pte_bits |= _PAGE_RW;
-
- if ((pteval & need_pte_bits) != need_pte_bits)
- return 0;
-
- return __pkru_allows_pkey(pte_flags_pkey(pteval), write);
-}
-
-#define pte_access_permitted pte_access_permitted
-static inline bool pte_access_permitted(pte_t pte, bool write)
-{
- return __pte_access_permitted(pte_val(pte), write);
-}
-
-#define pmd_access_permitted pmd_access_permitted
-static inline bool pmd_access_permitted(pmd_t pmd, bool write)
-{
- return __pte_access_permitted(pmd_val(pmd), write);
-}
-
-#define pud_access_permitted pud_access_permitted
-static inline bool pud_access_permitted(pud_t pud, bool write)
-{
- return __pte_access_permitted(pud_val(pud), write);
-}
-
#include <asm-generic/pgtable.h>
#endif /* __ASSEMBLY__ */