admin-guide/mm/pagemap.rst

12    physical frame each virtual page is mapped to.  It contains one 64-bit
16     * Bits 0-54  page frame number (PFN) if present
17     * Bits 0-4   swap type if swapped
18     * Bits 5-54  swap offset if swapped
19     * Bit  55    pte is soft-dirty (see
20       Documentation/admin-guide/mm/soft-dirty.rst)
22     * Bit  57    pte is uffd-wp write-protected (since 5.13) (see
23       Documentation/admin-guide/mm/userfaultfd.rst)
24     * Bits 58-60 zero
25     * Bit  61    page is file-page or shared-anon (since 3.5)
30    In 4.0 and 4.1 opens by unprivileged fail with -EPERM.  Starting from
44  * ``/proc/kpagecount``.  This file contains a 64-bit count of the number of
47 The page-types tool in the tools/mm directory can be used to query the
50  * ``/proc/kpageflags``.  This file contains a 64-bit set of flags for each
80     25. IDLE
83  * ``/proc/kpagecgroup``.  This file contains a 64-bit inode number of the
90 0 - LOCKED
93 7 - SLAB
97 10 - BUDDY
102 15 - COMPOUND_HEAD
106     pages are hugeTLB pages (Documentation/admin-guide/mm/hugetlbpage.rst),
110 16 - COMPOUND_TAIL
112 17 - HUGE
114 19 - HWPOISON
115     Hardware detected memory corruption on this page: don't touch the data!
116 20 - NOPAGE
118 21 - KSM
120 22 - THP
122 23 - OFFLINE
124 24 - ZERO_PAGE
126 25 - IDLE
127     The page has not been accessed since it was marked idle (see
128     Documentation/admin-guide/mm/idle_page_tracking.rst).
130     a PTE. To make sure the flag is up-to-date one has to read
132 26 - PGTABLE
136 ---------------------
138 1 - ERROR
140 3 - UPTODATE
141    The page has up-to-date data.
142    ie. for file backed page: (in-memory data revision >= on-disk one)
143 4 - DIRTY
145    i.e. for file backed page: (in-memory data revision >  on-disk one)
146 8 - WRITEBACK
150 ----------------------
152 5 - LRU
154 6 - ACTIVE
156 18 - UNEVICTABLE
157    The page is in the unevictable (non-)LRU list It is somehow pinned and
160 2 - REFERENCED
162 9 - RECLAIM
164 11 - MMAP
166 12 - ANON
168 13 - SWAPCACHE
170 14 - SWAPBACKED
173 The page-types tool in the tools/mm directory can be used to query the
184  2. Select the maps you are interested in -- all of them, or a particular
201 swapped out. This makes swapped out pages indistinguishable from never-allocated
212 holes (none/non-allocated) by specifying the SEEK_DATA flag on the file where
217 cache) and out of memory (swapped out or none/non-allocated).
222 Reading from any of the files will return -EINVAL if you are not starting
223 the read on an 8-byte boundary (e.g., if you sought an odd number of bytes
226 Before Linux 3.11 pagemap bits 55-60 were used for "page-shift" (which is
228 after first clear of soft-dirty bits. Since Linux 4.2 they are used for