linux/arch/x86
Dan Williams 1501899a89 mm: fix device-dax pud write-faults triggered by get_user_pages()
Currently only get_user_pages_fast() can safely handle the writable gup
case due to its use of pud_access_permitted() to check whether the pud
entry is writable.  In the gup slow path pud_write() is used instead of
pud_access_permitted() and to date it has been unimplemented, just calls
BUG_ON().

    kernel BUG at ./include/linux/hugetlb.h:244!
    [..]
    RIP: 0010:follow_devmap_pud+0x482/0x490
    [..]
    Call Trace:
     follow_page_mask+0x28c/0x6e0
     __get_user_pages+0xe4/0x6c0
     get_user_pages_unlocked+0x130/0x1b0
     get_user_pages_fast+0x89/0xb0
     iov_iter_get_pages_alloc+0x114/0x4a0
     nfs_direct_read_schedule_iovec+0xd2/0x350
     ? nfs_start_io_direct+0x63/0x70
     nfs_file_direct_read+0x1e0/0x250
     nfs_file_read+0x90/0xc0

For now this just implements a simple check for the _PAGE_RW bit similar
to pmd_write.  However, this implies that the gup-slow-path check is
missing the extra checks that the gup-fast-path performs with
pud_access_permitted.  Later patches will align all checks to use the
'access_permitted' helper if the architecture provides it.

Note that the generic 'access_permitted' helper fallback is the simple
_PAGE_RW check on architectures that do not define the
'access_permitted' helper(s).

[dan.j.williams@intel.com: fix powerpc compile error]
  Link: http://lkml.kernel.org/r/151129126165.37405.16031785266675461397.stgit@dwillia2-desk3.amr.corp.intel.com
Link: http://lkml.kernel.org/r/151043109938.2842.14834662818213616199.stgit@dwillia2-desk3.amr.corp.intel.com
Fixes: a00cc7d9dd ("mm, x86: add support for PUD-sized transparent hugepages")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Thomas Gleixner <tglx@linutronix.de>	[x86]
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-29 18:40:42 -08:00
..
boot x86/boot/KASLR: Remove unused variable 2017-11-23 20:17:59 +01:00
configs x86/unwind: Rename unwinder config options to 'CONFIG_UNWINDER_*' 2017-10-14 10:12:12 +02:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2017-11-14 10:52:09 -08:00
entry Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-26 14:11:54 -08:00
events Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-26 14:11:54 -08:00
hyperv Char/Misc patches for 4.15-rc1 2017-11-16 09:10:59 -08:00
ia32 License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
include mm: fix device-dax pud write-faults triggered by get_user_pages() 2017-11-29 18:40:42 -08:00
kernel Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-26 14:11:54 -08:00
kvm kvm: vmx: Allow disabling virtual NMI support 2017-11-17 13:20:07 +01:00
lib x86/decoder: Add new TEST instruction pattern 2017-11-24 08:36:12 +01:00
math-emu License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mm Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-26 14:11:54 -08:00
net bpf: fix bpf_tail_call() x64 JIT 2017-10-03 16:04:44 -07:00
oprofile Modules updates for v4.15 2017-11-15 13:46:33 -08:00
pci pci-v4.15-changes 2017-11-15 15:01:28 -08:00
platform kmemcheck: stop using GFP_NOTRACK and SLAB_NOTRACK 2017-11-15 18:21:04 -08:00
power License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
purgatory License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ras License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
realmode x86/realmode: Don't decrypt trampoline area under SEV 2017-11-07 15:35:55 +01:00
tools License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
um Merge branch 'linus' into x86/asm, to pick up fixes and resolve conflicts 2017-11-07 10:53:06 +01:00
video
xen xen: features and fixes for v4.15-rc1 2017-11-16 13:06:27 -08:00
.gitignore
Kbuild Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-09-07 09:25:15 -07:00
Kconfig Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-26 14:11:54 -08:00
Kconfig.cpu License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig.debug Merge branch 'linus' into x86/asm, to pick up fixes and resolve conflicts 2017-11-07 10:53:06 +01:00
Makefile kmemcheck: remove annotations 2017-11-15 18:21:04 -08:00
Makefile_32.cpu License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Makefile.um License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00