diff options
| -rw-r--r-- | man/man2/madvise.2 | 39 |
1 files changed, 29 insertions, 10 deletions
diff --git a/man/man2/madvise.2 b/man/man2/madvise.2 index bd2b90b7ad..be1ba17aeb 100644 --- a/man/man2/madvise.2 +++ b/man/man2/madvise.2 @@ -697,9 +697,24 @@ is applied to regions containing pre-existing lightweight guard regions, they are left in place. .IP -This operation is supported -only for writable anonymous private mappings -which have not been mlock'd. +Prior to Linux 6.15, +this operation was supported +only for writable anonymous private mappings. +Since Linux 6.15, +both anonymous and file-backed mappings are supported, +including read-only mappings. +.IP +The mapping must not be mlock'd, +map hugetlb ranges, +nor contain special mappings. +For example, +mappings marked with kernel-internal flags such as +.B VM_PFNMAP +or +.BR VM_IO , +or secret memory regions created using +.BR memfd_secret (2). +.IP An .B EINVAL error is returned if it is attempted on any other kind of mapping. @@ -756,19 +771,23 @@ and .IP All mappings in the range other than lightweight guard regions -are left in place -(including mlock'd mappings). -The operation is, -however, -valid only for writable anonymous private mappings, +are left in place. +The operation is supported on those mappings +permitted by +.B MADV_GUARD_INSTALL +in addition to mlock()'d mappings, returning an .B EINVAL error otherwise. .IP When lightweight guard regions are removed, they act as empty regions of the containing mapping. -Since only writable anonymous private mappings are supported, -they therefore become zero-fill-on-demand pages. +Therefore, +anonymous private mappings become +zero-fill-on-demand pages, +and file-backed mappings are repopulated with the +memory contents from the up-to-date contents of the +underlying mapped file. .IP If any transparent huge pages are encountered in the operation, they are left in place. |