diff options
| author | Lorenzo Stoakes <lorenzo.stoakes@oracle.com> | 2025-04-23 19:31:05 +0100 |
|---|---|---|
| committer | Alejandro Colomar <alx@kernel.org> | 2025-05-01 13:07:54 +0200 |
| commit | 9ee66d0b01dfc797c57b4735fd48c138f97a66d2 (patch) | |
| tree | 4cff8cf21bc25a047c61750fbf3cf613d85e016e | |
| parent | 45b9cf71bee8ddef75075966337a29e75185faee (diff) | |
| download | man-pages-9ee66d0b01dfc797c57b4735fd48c138f97a66d2.tar.gz | |
man/man2/madvise.2: Update MADV_GUARD_INSTALL, MADV_GUARD_REMOVE for Linux 6.15
Lightweight guard region support has been extended in Linux 6.15,
permitting the use of these features for file-backed and read-only
mappings.
Update the description for these operations in the madvise manpage to
describe the changed behaviour.
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Message-ID: <20250423183105.116978-1-lorenzo.stoakes@oracle.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
| -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. |