Make mmu_notifier_register() safer by issuing a memory barrier before
registering a new notifier.  This fixes a theoretical bug on weakly
ordered CPUs.  For example, take this simplified use of notifiers by a
driver:

	my_struct->mn.ops = &my_ops; /* (1) */
	mmu_notifier_register(&my_struct->mn, mm)
		...
		hlist_add_head(&mn->hlist, &mm->mmu_notifiers); /* (2) */
		...

Once mmu_notifier_register() releases the mm locks, another thread can
invalidate a range:

	mmu_notifier_invalidate_range()
		...
		hlist_for_each_entry_rcu(mn, &mm->mmu_notifiers, hlist) {
			if (mn->ops->invalidate_range)

The read side relies on the data dependency between mn and ops to ensure
that the pointer is properly initialized.  But the write side doesn't have
any dependency between (1) and (2), so they could be reordered and the
readers could dereference an invalid mn->ops.  mmu_notifier_register()
does take all the mm locks before adding to the hlist, but those have
acquire semantics which isn't sufficient.

By calling hlist_add_head_rcu() instead of hlist_add_head() we update the
hlist using a store-release, ensuring that readers see prior
initialization of my_struct.  This situation is better illustated by
litmus test MP+onceassign+derefonce.

Link: http://lkml.kernel.org/r/20190502133532.24981-1-jean-philippe.brucker@arm.com
Fixes: cddb8a5c ("mmu-notifiers: core")
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

If the caller asks us for offset == num, we should already fail in the
first check, i.e.  the one testing for offsets beyond the object.

At the moment, we are failing on the second test anyway, since count
cannot be 0.  Still, to agree with the comment of the first test, we
should first test it there.

Link: http://lkml.kernel.org/r/20190528193004.GA7744@gmail.comSigned-off-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Huang Ying <ying.huang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Drop the pgtable_t variable from all implementation for pte_fn_t as none
of them use it.  apply_to_pte_range() should stop computing it as well.
Should help us save some cycles.

Link: http://lkml.kernel.org/r/1556803126-26596-1-git-send-email-anshuman.khandual@arm.comSigned-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Acked-by: Matthew Wilcox <willy@infradead.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: <jglisse@redhat.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Replace __get_free_page() and alloc_pages() calls with the generic
__pte_alloc_one_kernel() and __pte_alloc_one().

There is no functional change for the kernel PTE allocation.

The difference for the user PTEs, is that the clear_pte_table() is now
called after pgtable_page_ctor() and the addition of __GFP_ACCOUNT to the
GFP flags.

The pte_free() and pte_free_kernel() versions are identical to the generic
ones and can be simply dropped.

Link: http://lkml.kernel.org/r/1557296232-15361-15-git-send-email-rppt@linux.ibm.comSigned-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Guo Ren <guoren@kernel.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sam Creasey <sammy@sammy.net>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Vincent Chen <deanbo422@gmail.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Guo Ren <ren_guo@c-sky.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

um allocates PTE pages with __get_free_page() and uses
GFP_KERNEL | __GFP_ZERO for the allocations.

Switch it to the generic version that does exactly the same thing for the
kernel page tables and adds __GFP_ACCOUNT for the user PTEs.

The pte_free() and pte_free_kernel() versions are identical to the generic
ones and can be simply dropped.

Link: http://lkml.kernel.org/r/1557296232-15361-14-git-send-email-rppt@linux.ibm.comSigned-off-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Acked-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Guo Ren <guoren@kernel.org>
Cc: Guo Ren <ren_guo@c-sky.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sam Creasey <sammy@sammy.net>
Cc: Vincent Chen <deanbo422@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The only difference between the generic and RISC-V implementation of PTE
allocation is the usage of __GFP_RETRY_MAYFAIL for both kernel and user
PTEs and the absence of __GFP_ACCOUNT for the user PTEs.

The conversion to the generic version removes the __GFP_RETRY_MAYFAIL and
ensures that GFP_ACCOUNT is used for the user PTE allocations.

The pte_free() and pte_free_kernel() versions are identical to the generic
ones and can be simply dropped.

Link: http://lkml.kernel.org/r/1557296232-15361-13-git-send-email-rppt@linux.ibm.comSigned-off-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Guo Ren <guoren@kernel.org>
Cc: Guo Ren <ren_guo@c-sky.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sam Creasey <sammy@sammy.net>
Cc: Vincent Chen <deanbo422@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parisc allocates PTE pages with __get_free_page() and uses
GFP_KERNEL | __GFP_ZERO for the allocations.

Switch it to the generic version that does exactly the same thing for the
kernel page tables and adds __GFP_ACCOUNT for the user PTEs.

The pte_free_kernel() and pte_free() versions on are identical to the
generic ones and can be simply dropped.

Link: http://lkml.kernel.org/r/1557296232-15361-12-git-send-email-rppt@linux.ibm.comSigned-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Guo Ren <guoren@kernel.org>
Cc: Guo Ren <ren_guo@c-sky.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sam Creasey <sammy@sammy.net>
Cc: Vincent Chen <deanbo422@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nios2 allocates kernel PTE pages with

        __get_free_pages(GFP_KERNEL | __GFP_ZERO, PTE_ORDER);

and user page tables with

        pte = alloc_pages(GFP_KERNEL, PTE_ORDER);
        if (pte)
                clear_highpage();

The PTE_ORDER is hardwired to zero, which makes nios2 implementation almost
identical to the generic one.

Switch nios2 to the generic version that does exactly the same thing for
the kernel page tables and adds __GFP_ACCOUNT for the user PTEs.

The pte_free_kernel() and pte_free() versions on nios2 are identical to the
generic ones and can be simply dropped.

Link: http://lkml.kernel.org/r/1557296232-15361-11-git-send-email-rppt@linux.ibm.comSigned-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Guo Ren <guoren@kernel.org>
Cc: Guo Ren <ren_guo@c-sky.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sam Creasey <sammy@sammy.net>
Cc: Vincent Chen <deanbo422@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The nds32 implementation of pte_alloc_one_kernel() differs from the
generic in the use of __GFP_RETRY_MAYFAIL flag, which is removed after the
conversion.

The nds32 version of pte_alloc_one() missed the call to
pgtable_page_ctor() and also used __GFP_RETRY_MAYFAIL.  Switching it to
use generic __pte_alloc_one() for the PTE page allocation ensures that
page table constructor is run and the user page tables are allocated with
__GFP_ACCOUNT.

The conversion to the generic version of pte_free_kernel() removes the
NULL check for pte.

The pte_free() version on nds32 is identical to the generic one and can be
simply dropped.

Link: http://lkml.kernel.org/r/1557296232-15361-10-git-send-email-rppt@linux.ibm.comSigned-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Guo Ren <guoren@kernel.org>
Cc: Guo Ren <ren_guo@c-sky.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sam Creasey <sammy@sammy.net>
Cc: Vincent Chen <deanbo422@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

MIPS allocates kernel PTE pages with

	__get_free_pages(GFP_KERNEL | __GFP_ZERO, PTE_ORDER)

and user PTE pages with

	pte = alloc_pages(GFP_KERNEL, PTE_ORDER)

and then uses clear_highpage(pte) to zero out the allocated page for the
user page tables.

The PTE_ORDER is hardwired to zero, which makes MIPS implementation almost
identical to the generic one.

Switch MIPS to the generic version that does exactly the same thing for the
kernel page tables and adds __GFP_ACCOUNT for the user PTEs.

The pte_free_kernel() and pte_free() versions on mips are identical to the
generic ones and can be simply dropped.

Link: http://lkml.kernel.org/r/1557296232-15361-9-git-send-email-rppt@linux.ibm.comSigned-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Paul Burton <paul.burton@mips.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Guo Ren <guoren@kernel.org>
Cc: Guo Ren <ren_guo@c-sky.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sam Creasey <sammy@sammy.net>
Cc: Vincent Chen <deanbo422@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The sun3 MMU variant of m68k uses GFP_KERNEL to allocate a PTE page and
then memset(0) or clear_highpage() to clear it.

This is equivalent to allocating the page with GFP_KERNEL | __GFP_ZERO,
which allows replacing sun3 implementation of pte_alloc_one() and
pte_alloc_one_kernel() with the generic ones.

The pte_free() and pte_free_kernel() versions are identical to the generic
ones and can be simply dropped.

Link: http://lkml.kernel.org/r/1557296232-15361-8-git-send-email-rppt@linux.ibm.comSigned-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Guo Ren <guoren@kernel.org>
Cc: Guo Ren <ren_guo@c-sky.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sam Creasey <sammy@sammy.net>
Cc: Vincent Chen <deanbo422@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The csky implementation pte_alloc_one(), pte_free_kernel() and pte_free()
is identical to the generic except of lack of __GFP_ACCOUNT for the user
PTEs allocation.

Switch csky to use generic version of these functions.

The csky implementation of pte_alloc_one_kernel() is not replaced because
it does not clear the allocated page but rather sets each PTE in it to a
non-zero value.

The pte_free_kernel() and pte_free() versions on csky are identical to the
generic ones and can be simply dropped.

Link: http://lkml.kernel.org/r/1557296232-15361-6-git-send-email-rppt@linux.ibm.comSigned-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Guo Ren <ren_guo@c-sky.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Guo Ren <guoren@kernel.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sam Creasey <sammy@sammy.net>
Cc: Vincent Chen <deanbo422@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The PTE allocations in arm64 are identical to the generic ones modulo the
GFP flags.

Using the generic pte_alloc_one() functions ensures that the user page
tables are allocated with __GFP_ACCOUNT set.

The arm64 definition of PGALLOC_GFP is removed and replaced with
GFP_PGTABLE_USER for p[gum]d_alloc_one() for the user page tables and
GFP_PGTABLE_KERNEL for the kernel page tables. The KVM memory cache is now
using GFP_PGTABLE_USER.

The mappings created with create_pgd_mapping() are now using
GFP_PGTABLE_KERNEL.

The conversion to the generic version of pte_free_kernel() removes the NULL
check for pte.

The pte_free() version on arm64 is identical to the generic one and
can be simply dropped.

[cai@lca.pw: fix a bogus GFP flag in pgd_alloc()]
  Link: https://lore.kernel.org/r/1559656836-24940-1-git-send-email-cai@lca.pw/
[and fix it more]
  Link: https://lore.kernel.org/linux-mm/20190617151252.GF16810@rapoport-lnx/
Link: http://lkml.kernel.org/r/1557296232-15361-5-git-send-email-rppt@linux.ibm.comSigned-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Guo Ren <guoren@kernel.org>
Cc: Guo Ren <ren_guo@c-sky.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sam Creasey <sammy@sammy.net>
Cc: Vincent Chen <deanbo422@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Replace __get_free_page() and alloc_pages() calls with the generic
__pte_alloc_one_kernel() and __pte_alloc_one().

There is no functional change for the kernel PTE allocation.

The difference for the user PTEs, is that the clear_pte_table() is now
called after pgtable_page_ctor() and the addition of __GFP_ACCOUNT to the
GFP flags.

The conversion to the generic version of pte_free_kernel() removes the NULL
check for pte.

The pte_free() version on arm is identical to the generic one and can be
simply dropped.

Link: http://lkml.kernel.org/r/1557296232-15361-4-git-send-email-rppt@linux.ibm.comSigned-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Guo Ren <guoren@kernel.org>
Cc: Guo Ren <ren_guo@c-sky.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sam Creasey <sammy@sammy.net>
Cc: Vincent Chen <deanbo422@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

alpha allocates PTE pages with __get_free_page() and uses
GFP_KERNEL | __GFP_ZERO for the allocations.

Switch it to the generic version that does exactly the same thing for the
kernel page tables and adds __GFP_ACCOUNT for the user PTEs.

The alpha pte_free() and pte_free_kernel() versions are identical to the
generic ones and can be simply dropped.

Link: http://lkml.kernel.org/r/1557296232-15361-3-git-send-email-rppt@linux.ibm.comSigned-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Guo Ren <guoren@kernel.org>
Cc: Guo Ren <ren_guo@c-sky.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sam Creasey <sammy@sammy.net>
Cc: Vincent Chen <deanbo422@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Most architectures have identical or very similar implementation of
pte_alloc_one_kernel(), pte_alloc_one(), pte_free_kernel() and
pte_free().

Add a generic implementation that can be reused across architectures and
enable its use on x86.

The generic implementation uses

	GFP_KERNEL | __GFP_ZERO

for the kernel page tables and

	GFP_KERNEL | __GFP_ZERO | __GFP_ACCOUNT

for the user page tables.

The "base" functions for PTE allocation, namely __pte_alloc_one_kernel()
and __pte_alloc_one() are intended for the architectures that require
additional actions after actual memory allocation or must use non-default
GFP flags.

x86 is switched to use generic pte_alloc_one_kernel(), pte_free_kernel() and
pte_free().

x86 still implements pte_alloc_one() to allow run-time control of GFP
flags required for "userpte" command line option.

Link: http://lkml.kernel.org/r/1557296232-15361-2-git-send-email-rppt@linux.ibm.comSigned-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Guo Ren <guoren@kernel.org>
Cc: Guo Ren <ren_guo@c-sky.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sam Creasey <sammy@sammy.net>
Cc: Vincent Chen <deanbo422@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Several mips builds generate the following build warning.

  mm/gup.c:1788:13: warning: 'undo_dev_pagemap' defined but not used

The function is declared unconditionally but only called from behind
various ifdefs. Mark it __maybe_unused.

Link: http://lkml.kernel.org/r/1562072523-22311-1-git-send-email-linux@roeck-us.netSigned-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

If we end up without a PGD or PUD entry backing the gate area, don't BUG
-- just fail gracefully.

It's not entirely implausible that this could happen some day on x86.  It
doesn't right now even with an execute-only emulated vsyscall page because
the fixmap shares the PUD, but the core mm code shouldn't rely on that
particular detail to avoid OOPSing.

Link: http://lkml.kernel.org/r/a1d9f4efb75b9d464e59fd6af00104b21c58f6f7.1561610798.git.luto@kernel.orgSigned-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Both hugetlb and thp locate on the same migration type of pageblock, since
they are allocated from a free_list[].  Based on this fact, it is enough
to check on a single subpage to decide the migration type of the whole
huge page.  By this way, it saves (2M/4K - 1) times loop for pmd_huge on
x86, similar on other archs.

Furthermore, when executing isolate_huge_page(), it avoid taking global
hugetlb_lock many times, and meanless remove/add to the local link list
cma_page_list.

[akpm@linux-foundation.org: make `i' and `step' unsigned]
Link: http://lkml.kernel.org/r/1561612545-28997-1-git-send-email-kernelfans@gmail.comSigned-off-by: Pingfan Liu <kernelfans@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

All other get_user_page_fast cases mark the page referenced, so do this
here as well.

Link: http://lkml.kernel.org/r/20190625143715.1689-17-hch@lst.deSigned-off-by: Christoph Hellwig <hch@lst.de>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Miller <davem@davemloft.net>
Cc: James Hogan <jhogan@kernel.org>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This applies the overflow fixes from 8fde12ca ("mm: prevent
get_user_pages() from overflowing page refcount") to the powerpc hugepd
code and brings it back in sync with the other GUP cases.

Link: http://lkml.kernel.org/r/20190625143715.1689-16-hch@lst.deSigned-off-by: Christoph Hellwig <hch@lst.de>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Miller <davem@davemloft.net>
Cc: James Hogan <jhogan@kernel.org>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

While only powerpc supports the hugepd case, the code is pretty generic
and I'd like to keep all GUP internals in one place.

Link: http://lkml.kernel.org/r/20190625143715.1689-15-hch@lst.deSigned-off-by: Christoph Hellwig <hch@lst.de>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Miller <davem@davemloft.net>
Cc: James Hogan <jhogan@kernel.org>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

We can only deal with FOLL_WRITE and/or FOLL_LONGTERM in
get_user_pages_fast, so reject all other flags.

Link: http://lkml.kernel.org/r/20190625143715.1689-14-hch@lst.deSigned-off-by: Christoph Hellwig <hch@lst.de>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Miller <davem@davemloft.net>
Cc: James Hogan <jhogan@kernel.org>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Always build mm/gup.c so that we don't have to provide separate nommu
stubs.  Also merge the get_user_pages_fast and __get_user_pages_fast stubs
when HAVE_FAST_GUP into the main implementations, which will never call
the fast path if HAVE_FAST_GUP is not set.

This also ensures the new put_user_pages* helpers are available for nommu,
as those are currently missing, which would create a problem as soon as we
actually grew users for it.

Link: http://lkml.kernel.org/r/20190625143715.1689-13-hch@lst.deSigned-off-by: Christoph Hellwig <hch@lst.de>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Miller <davem@davemloft.net>
Cc: James Hogan <jhogan@kernel.org>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This moves the actually exported functions towards the end of the file,
and reorders some functions to be in more logical blocks as a preparation
for moving various stubs inline into the main functionality using
IS_ENABLED().

Link: http://lkml.kernel.org/r/20190625143715.1689-12-hch@lst.deSigned-off-by: Christoph Hellwig <hch@lst.de>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Miller <davem@davemloft.net>
Cc: James Hogan <jhogan@kernel.org>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

We only support the generic GUP now, so rename the config option to
be more clear, and always use the mm/Kconfig definition of the
symbol and select it from the arch Kconfigs.

Link: http://lkml.kernel.org/r/20190625143715.1689-11-hch@lst.deSigned-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Miller <davem@davemloft.net>
Cc: James Hogan <jhogan@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The sparc64 code is mostly equivalent to the generic one, minus various
bugfixes and two arch overrides that this patch adds to pgtable.h.

Link: http://lkml.kernel.org/r/20190625143715.1689-10-hch@lst.deSigned-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>
Cc: David Miller <davem@davemloft.net>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Add a helper to untag a user pointer.  This is needed for ADI support
in get_user_pages_fast.

Link: http://lkml.kernel.org/r/20190625143715.1689-9-hch@lst.deSigned-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>
Cc: David Miller <davem@davemloft.net>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sparc64 only had pgd_page_vaddr, but not pgd_page.

[hch@lst.de: fix sparc64 build]
  Link: http://lkml.kernel.org/r/20190626131318.GA5101@lst.de
Link: http://lkml.kernel.org/r/20190625143715.1689-8-hch@lst.deSigned-off-by: Christoph Hellwig <hch@lst.de>
Cc: David Miller <davem@davemloft.net>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The sh code is mostly equivalent to the generic one, minus various
bugfixes and two arch overrides that this patch adds to pgtable.h.

Link: http://lkml.kernel.org/r/20190625143715.1689-7-hch@lst.deSigned-off-by: Christoph Hellwig <hch@lst.de>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Miller <davem@davemloft.net>
Cc: James Hogan <jhogan@kernel.org>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sh only had pud_page_vaddr, but not pud_page.

[hch@lst.de: sh: stub out pud_page]
  Link: http://lkml.kernel.org/r/20190701151818.32227-2-hch@lst.de
Link: http://lkml.kernel.org/r/20190625143715.1689-6-hch@lst.deSigned-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Miller <davem@davemloft.net>
Cc: James Hogan <jhogan@kernel.org>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The mips code is mostly equivalent to the generic one, minus various
bugfixes and an arch override for gup_fast_permitted.

Note that this defines ARCH_HAS_PTE_SPECIAL for mips as mips has
pte_special and pte_mkspecial implemented and used in the existing gup
code.  They are no-op stubs, though which makes me a little unsure if this
is really right thing to do.

Note that this also adds back a missing cpu_has_dc_aliases check for
__get_user_pages_fast, which the old code was only doing for
get_user_pages_fast.  This clearly looks like an oversight, as any
condition that makes get_user_pages_fast unsafe also applies to
__get_user_pages_fast.

[hch@lst.de: MIPS: don't select ARCH_HAS_PTE_SPECIAL]
  Link: http://lkml.kernel.org/r/20190701151818.32227-3-hch@lst.de
Link: http://lkml.kernel.org/r/20190625143715.1689-5-hch@lst.deSigned-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Miller <davem@davemloft.net>
Cc: James Hogan <jhogan@kernel.org>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The split low/high access is the only non-READ_ONCE version of gup_get_pte
that did show up in the various arch implemenations.  Lift it to common
code and drop the ifdef based arch override.

Link: http://lkml.kernel.org/r/20190625143715.1689-4-hch@lst.deSigned-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Miller <davem@davemloft.net>
Cc: James Hogan <jhogan@kernel.org>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pass in the already calculated end value instead of recomputing it, and
leave the end > start check in the callers instead of duplicating them in
the arch code.

Link: http://lkml.kernel.org/r/20190625143715.1689-3-hch@lst.deSigned-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Miller <davem@davemloft.net>
Cc: James Hogan <jhogan@kernel.org>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Patch series "switch the remaining architectures to use generic GUP", v4.

A series to switch mips, sh and sparc64 to use the generic GUP code so
that we only have one codebase to touch for further improvements to this
code.

This patch (of 16):

This will allow sparc64, or any future architecture with memory tagging to
override its tags for get_user_pages and get_user_pages_fast.

Link: http://lkml.kernel.org/r/20190625143715.1689-2-hch@lst.deSigned-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: David Miller <davem@davemloft.net>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

There are concerns about memory leaks from extensive use of memory cgroups
as each memory cgroup creates its own set of kmem caches.  There is a
possiblity that the memcg kmem caches may remain even after the memory
cgroups have been offlined.  Therefore, it will be useful to show the
status of each of memcg kmem caches.

This patch introduces a new <debugfs>/memcg_slabinfo file which is
somewhat similar to /proc/slabinfo in format, but lists only information
about kmem caches that have child memcg kmem caches.  Information
available in /proc/slabinfo are not repeated in memcg_slabinfo.

A portion of a sample output of the file was:

  # <name> <css_id[:dead]> <active_objs> <num_objs> <active_slabs> <num_slabs>
  rpc_inode_cache   root          13     51      1      1
  rpc_inode_cache     48           0      0      0      0
  fat_inode_cache   root           1     45      1      1
  fat_inode_cache     41           2     45      1      1
  xfs_inode         root         770    816     24     24
  xfs_inode           92          22     34      1      1
  xfs_inode           88:dead      1     34      1      1
  xfs_inode           89:dead     23     34      1      1
  xfs_inode           85           4     34      1      1
  xfs_inode           84           9     34      1      1

The css id of the memcg is also listed. If a memcg is not online,
the tag ":dead" will be attached as shown above.

[longman@redhat.com: memcg: add ":deact" tag for reparented kmem caches in memcg_slabinfo]
  Link: http://lkml.kernel.org/r/20190621173005.31514-1-longman@redhat.com
[longman@redhat.com: set the flag in the common code as suggested by Roman]
  Link: http://lkml.kernel.org/r/20190627184324.5875-1-longman@redhat.com
Link: http://lkml.kernel.org/r/20190619171621.26209-1-longman@redhat.comSigned-off-by: Waiman Long <longman@redhat.com>
Suggested-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Let's reparent non-root kmem_caches on memcg offlining.  This allows us to
release the memory cgroup without waiting for the last outstanding kernel
object (e.g.  dentry used by another application).

Since the parent cgroup is already charged, everything we need to do is to
splice the list of kmem_caches to the parent's kmem_caches list, swap the
memcg pointer, drop the css refcounter for each kmem_cache and adjust the
parent's css refcounter.

Please, note that kmem_cache->memcg_params.memcg isn't a stable pointer
anymore.  It's safe to read it under rcu_read_lock(), cgroup_mutex held,
or any other way that protects the memory cgroup from being released.

We can race with the slab allocation and deallocation paths.  It's not a
big problem: parent's charge and slab global stats are always correct, and
we don't care anymore about the child usage and global stats.  The child
cgroup is already offline, so we don't use or show it anywhere.

Local slab stats (NR_SLAB_RECLAIMABLE and NR_SLAB_UNRECLAIMABLE) aren't
used anywhere except count_shadow_nodes().  But even there it won't break
anything: after reparenting "nodes" will be 0 on child level (because
we're already reparenting shrinker lists), and on parent level page stats
always were 0, and this patch won't change anything.

[guro@fb.com: properly handle kmem_caches reparented to root_mem_cgroup]
  Link: http://lkml.kernel.org/r/20190620213427.1691847-1-guro@fb.com
Link: http://lkml.kernel.org/r/20190611231813.3148843-11-guro@fb.comSigned-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Waiman Long <longman@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Every slab page charged to a non-root memory cgroup has a pointer to the
memory cgroup and holds a reference to it, which protects a non-empty
memory cgroup from being released.  At the same time the page has a
pointer to the corresponding kmem_cache, and also hold a reference to the
kmem_cache.  And kmem_cache by itself holds a reference to the cgroup.

So there is clearly some redundancy, which allows to stop setting the
page->mem_cgroup pointer and rely on getting memcg pointer indirectly via
kmem_cache.  Further it will allow to change this pointer easier, without
a need to go over all charged pages.

So let's stop setting page->mem_cgroup pointer for slab pages, and stop
using the css refcounter directly for protecting the memory cgroup from
going away.  Instead rely on kmem_cache as an intermediate object.

Make sure that vmstats and shrinker lists are working as previously, as
well as /proc/kpagecgroup interface.

Link: http://lkml.kernel.org/r/20190611231813.3148843-10-guro@fb.comSigned-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Waiman Long <longman@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Currently each charged slab page holds a reference to the cgroup to which
it's charged.  Kmem_caches are held by the memcg and are released all
together with the memory cgroup.  It means that none of kmem_caches are
released unless at least one reference to the memcg exists, which is very
far from optimal.

Let's rework it in a way that allows releasing individual kmem_caches as
soon as the cgroup is offline, the kmem_cache is empty and there are no
pending allocations.

To make it possible, let's introduce a new percpu refcounter for non-root
kmem caches.  The counter is initialized to the percpu mode, and is
switched to the atomic mode during kmem_cache deactivation.  The counter
is bumped for every charged page and also for every running allocation.
So the kmem_cache can't be released unless all allocations complete.

To shutdown non-active empty kmem_caches, let's reuse the work queue,
previously used for the kmem_cache deactivation.  Once the reference
counter reaches 0, let's schedule an asynchronous kmem_cache release.

* I used the following simple approach to test the performance
(stolen from another patchset by T. Harding):

    time find / -name fname-no-exist
    echo 2 > /proc/sys/vm/drop_caches
    repeat 10 times

Results:

        orig		patched

real	0m1.455s	real	0m1.355s
user	0m0.206s	user	0m0.219s
sys	0m0.855s	sys	0m0.807s

real	0m1.487s	real	0m1.699s
user	0m0.221s	user	0m0.256s
sys	0m0.806s	sys	0m0.948s

real	0m1.515s	real	0m1.505s
user	0m0.183s	user	0m0.215s
sys	0m0.876s	sys	0m0.858s

real	0m1.291s	real	0m1.380s
user	0m0.193s	user	0m0.198s
sys	0m0.843s	sys	0m0.786s

real	0m1.364s	real	0m1.374s
user	0m0.180s	user	0m0.182s
sys	0m0.868s	sys	0m0.806s

real	0m1.352s	real	0m1.312s
user	0m0.201s	user	0m0.212s
sys	0m0.820s	sys	0m0.761s

real	0m1.302s	real	0m1.349s
user	0m0.205s	user	0m0.203s
sys	0m0.803s	sys	0m0.792s

real	0m1.334s	real	0m1.301s
user	0m0.194s	user	0m0.201s
sys	0m0.806s	sys	0m0.779s

real	0m1.426s	real	0m1.434s
user	0m0.216s	user	0m0.181s
sys	0m0.824s	sys	0m0.864s

real	0m1.350s	real	0m1.295s
user	0m0.200s	user	0m0.190s
sys	0m0.842s	sys	0m0.811s

So it looks like the difference is not noticeable in this test.

[cai@lca.pw: fix an use-after-free in kmemcg_workfn()]
  Link: http://lkml.kernel.org/r/1560977573-10715-1-git-send-email-cai@lca.pw
Link: http://lkml.kernel.org/r/20190611231813.3148843-9-guro@fb.comSigned-off-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Qian Cai <cai@lca.pw>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Waiman Long <longman@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Currently the memcg_params.dying flag and the corresponding workqueue used
for the asynchronous deactivation of kmem_caches is synchronized using the
slab_mutex.

It makes impossible to check this flag from the irq context, which will be
required in order to implement asynchronous release of kmem_caches.

So let's switch over to the irq-save flavor of the spinlock-based
synchronization.

Link: http://lkml.kernel.org/r/20190611231813.3148843-8-guro@fb.comSigned-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Waiman Long <longman@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>