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![Song Liu](https://secure.gravatar.com/avatar/7321f956cd75bed4aa420d243b739af6.jpg?s=96&d=mm)
Song Liu committed 99cb0dbd47a
mm,thp: add read-only THP support for (non-shmem) FS This patch is (hopefully) the first step to enable THP for non-shmem filesystems. This patch enables an application to put part of its text sections to THP via madvise, for example: madvise((void *)0x600000, 0x200000, MADV_HUGEPAGE); We tried to reuse the logic for THP on tmpfs. Currently, write is not supported for non-shmem THP. khugepaged will only process vma with VM_DENYWRITE. sys_mmap() ignores VM_DENYWRITE requests (see ksys_mmap_pgoff). The only way to create vma with VM_DENYWRITE is execve(). This requirement limits non-shmem THP to text sections. The next patch will handle writes, which would only happen when the all the vmas with VM_DENYWRITE are unmapped. An EXPERIMENTAL config, READ_ONLY_THP_FOR_FS, is added to gate this feature. [songliubraving@fb.com: fix build without CONFIG_SHMEM] Link: http://lkml.kernel.org/r/F53407FB-96CC-42E8-9862-105C92CC2B98@fb.com [songliubraving@fb.com: fix double unlock in collapse_file()] Link: http://lkml.kernel.org/r/B960CBFA-8EFC-4DA4-ABC5-1977FFF2CA57@fb.com Link: http://lkml.kernel.org/r/20190801184244.3169074-7-songliubraving@fb.com Signed-off-by: Song Liu <songliubraving@fb.com> Acked-by: Rik van Riel <riel@surriel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Hugh Dickins <hughd@google.com> Cc: William Kucharski <william.kucharski@oracle.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>