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authorSong Liu <songliubraving@fb.com>2019-09-23 15:38:00 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-09-24 15:54:11 -0700
commit99cb0dbd47a15d395bf3faa78dc122bc5efe3fc0 (patch)
tree58e5902f24cd4a5b024152f5bd42a3589ff431cb /mm/rmap.c
parent579c571e2efdb8e5b50959ae66b6142e05bd704f (diff)
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>
Diffstat (limited to 'mm/rmap.c')
-rw-r--r--mm/rmap.c12
1 files changed, 8 insertions, 4 deletions
diff --git a/mm/rmap.c b/mm/rmap.c
index 26006445c8b5..d9a23bb773bf 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1189,8 +1189,10 @@ void page_add_file_rmap(struct page *page, bool compound)
}
if (!atomic_inc_and_test(compound_mapcount_ptr(page)))
goto out;
- VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
- __inc_node_page_state(page, NR_SHMEM_PMDMAPPED);
+ if (PageSwapBacked(page))
+ __inc_node_page_state(page, NR_SHMEM_PMDMAPPED);
+ else
+ __inc_node_page_state(page, NR_FILE_PMDMAPPED);
} else {
if (PageTransCompound(page) && page_mapping(page)) {
VM_WARN_ON_ONCE(!PageLocked(page));
@@ -1229,8 +1231,10 @@ static void page_remove_file_rmap(struct page *page, bool compound)
}
if (!atomic_add_negative(-1, compound_mapcount_ptr(page)))
goto out;
- VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
- __dec_node_page_state(page, NR_SHMEM_PMDMAPPED);
+ if (PageSwapBacked(page))
+ __dec_node_page_state(page, NR_SHMEM_PMDMAPPED);
+ else
+ __dec_node_page_state(page, NR_FILE_PMDMAPPED);
} else {
if (!atomic_add_negative(-1, &page->_mapcount))
goto out;