diff options
| author | Song Liu <songliubraving@fb.com> | 2019-09-23 15:38:00 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-09-24 15:54:11 -0700 |
| commit | 99cb0dbd47a15d395bf3faa78dc122bc5efe3fc0 (patch) | |
| tree | 58e5902f24cd4a5b024152f5bd42a3589ff431cb /mm/rmap.c | |
| parent | 579c571e2efdb8e5b50959ae66b6142e05bd704f (diff) | |
| download | lwn-99cb0dbd47a15d395bf3faa78dc122bc5efe3fc0.tar.gz lwn-99cb0dbd47a15d395bf3faa78dc122bc5efe3fc0.zip | |
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.c | 12 |
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; |