Document the new flags for mmap() and mlockall() and their behavior. Inlcude a change to getrlimit(2) to cover interactions with RLIMIT_MEMLOCK. These new flags will be introduced with the 4.2 kernel. Signed-off-by: Eric B Munson <emunson@xxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: linux-api@xxxxxxxxxxxxxxx Cc: linux-mm@xxxxxxxxx Cc: linux-man@xxxxxxxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx --- man2/getrlimit.2 | 9 +++++++-- man2/mlock.2 | 28 ++++++++++++++++++++++++++-- man2/mmap.2 | 21 +++++++++++++++++++++ 3 files changed, 54 insertions(+), 4 deletions(-) diff --git a/man2/getrlimit.2 b/man2/getrlimit.2 index ec464fe..729197e 100644 --- a/man2/getrlimit.2 +++ b/man2/getrlimit.2 @@ -215,7 +215,9 @@ and and the .BR mmap (2) .B MAP_LOCKED -operation. +or +.B MAP_LOCKONFAULT +operations. Since Linux 2.6.9 it also affects the .BR shmctl (2) .B SHM_LOCK @@ -232,7 +234,10 @@ locks established by .BR mlockall (2), and .BR mmap (2) -.BR MAP_LOCKED ; +with +.B MAP_LOCKED +or +.BR MAP_LOCKONFAULT ; a process can lock bytes up to this limit in each of these two categories. In Linux kernels before 2.6.9, this limit controlled the amount of diff --git a/man2/mlock.2 b/man2/mlock.2 index b8487ff..139a7be 100644 --- a/man2/mlock.2 +++ b/man2/mlock.2 @@ -96,9 +96,31 @@ process in the future. These could be for instance new pages required by a growing heap and stack as well as new memory-mapped files or shared memory regions. +.B MCL_FUTURE +will attempt to make all pages present when the address +space is allocated. +.TP +.BR MCL_ONFAULT " (since Linux 4.2)" +Like +.BR MCL_FUTURE , +but +.B MCL_ONFAULT +does not attempt to make all pages present when the address space is +allocated, instead wait until each page is accessed for the first +time before locking. Note that as with the difference between +.B MAP_LOCKED +and +.B MAP_LOCKONFAULT +for +.BR mmap "(2)," +the caller is charged for the entire allocated address space. See +.BR setrlimit "(2)" +for more details on resource limits. .PP If .B MCL_FUTURE +or +.B MCL_ONFAULT has been specified, then a later system call (e.g., .BR mmap (2), .BR sbrk (2), @@ -250,9 +272,11 @@ or when the process terminates. The .BR mlockall () .B MCL_FUTURE -setting is not inherited by a child created via +and +.B MCL_ONFAULT +settings are not inherited by a child created via .BR fork (2) -and is cleared during an +and are cleared during an .BR execve (2). The memory lock on an address range is automatically removed diff --git a/man2/mmap.2 b/man2/mmap.2 index a865612..5aa29e9 100644 --- a/man2/mmap.2 +++ b/man2/mmap.2 @@ -277,6 +277,26 @@ of the mapping. This flag is ignored in older kernels. .\" If set, the mapped pages will not be swapped out. .TP +.BR MAP_LOCKONFAULT " (since Linux 4.2)" +Lock pages covered by this mapping after they are +accessed for the first time. Unlike +.BR MAP_LOCKED , +.B MAP_LOCKONFAULT +does not attempt to populate the mapping immediately. Note that while +.B MAP_LOCKONFAULT +does not populate the mapping, the caller is charged for the full mapping +against +.B RLIMIT_MEMLOCK +when the mapping is created. This allows +.BR mmap "(2)" +calls to fail the same way for +.B MAP_LOCKED +and +.B MAP_LOCKONFAULT +when the resource limit would be exceeded. See +.BR setrlimit "(2)" +for more details on resource limits. +.TP .BR MAP_NONBLOCK " (since Linux 2.5.46)" Only meaningful in conjunction with .BR MAP_POPULATE . @@ -618,6 +638,7 @@ The relevant flags are: .BR MAP_GROWSDOWN , .BR MAP_HUGETLB , .BR MAP_LOCKED , +.BR MAP_LOCKONFAULT , .BR MAP_NONBLOCK , .BR MAP_NORESERVE , .BR MAP_POPULATE , -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
