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Hugh Dickins 352e32f894 mm/thp: make is_huge_zero_pmd() safe and quicker BugLink: https://bugs.launchpad.net/bugs/1936242 commit `3b77e8c8cd` upstream. Most callers of is_huge_zero_pmd() supply a pmd already verified present; but a few (notably zap_huge_pmd()) do not - it might be a pmd migration entry, in which the pfn is encoded differently from a present pmd: which might pass the is_huge_zero_pmd() test (though not on x86, since L1TF forced us to protect against that); or perhaps even crash in pmd_page() applied to a swap-like entry. Make it safe by adding pmd_present() check into is_huge_zero_pmd() itself; and make it quicker by saving huge_zero_pfn, so that is_huge_zero_pmd() will not need to do that pmd_page() lookup each time. __split_huge_pmd_locked() checked pmd_trans_huge() before: that worked, but is unnecessary now that is_huge_zero_pmd() checks present. Link: https://lkml.kernel.org/r/21ea9ca-a1f5-8b90-5e88-95fb1c49bbfa@google.com Fixes: `e71769ae52` ("mm: enable thp migration for shmem thp") Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Yang Shi <shy828301@gmail.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Jan Kara <jack@suse.cz> Cc: Jue Wang <juew@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Xu <peterx@redhat.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Wang Yugui <wangyugui@e16-tech.com> Cc: Zi Yan <ziy@nvidia.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Kamal Mostafa <kamal@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>		2021-08-13 09:44:26 +02:00
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arch	PCI: Add AMD RS690 quirk to enable 64-bit DMA	2021-08-13 09:44:23 +02:00
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debian	…
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drivers	i2c: robotfuzz-osif: fix control-request directions	2021-08-13 09:44:24 +02:00
fs	nilfs2: fix memory leak in nilfs_sysfs_delete_device_group	2021-08-13 09:44:24 +02:00
include	mm/thp: make is_huge_zero_pmd() safe and quicker	2021-08-13 09:44:26 +02:00
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kernel	kthread: prevent deadlock when kthread_mod_delayed_work() races with kthread_cancel_delayed_work_sync()	2021-08-13 09:44:25 +02:00
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mm	mm/thp: make is_huge_zero_pmd() safe and quicker	2021-08-13 09:44:26 +02:00
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scripts	recordmcount: Correct st_shndx handling	2021-08-13 09:44:22 +02:00
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tools	KVM: selftests: Fix kvm_check_cap() assertion	2021-08-13 09:44:22 +02:00
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virt	KVM: do not allow mapping valid but non-reference-counted pages	2021-08-13 09:44:24 +02:00
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README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.