LDP
/
man-pages
mirror of https://github.com/mkerrisk/man-pages
0
1
Fork 0
Code Releases Activity

mremap.2: Describe some use cases for MREMAP_DONTUNMAP 

Reported-by: Brian Geffon <bgeffon@google.com>
Reported-by: Lokesh Gidra <lokeshgidra@google.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Michael Kerrisk 2020-04-22 14:04:58 +02:00
parent 0367239919
commit a47ce0632c
1 changed files with 29 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
man2/mremap.2
View File

@ -145,9 +145,8 @@ The
.BR MREMAP_DONTUNMAP
flag may be used to atomically move a mapping while leaving the source
mapped.
Possible applications for this behavior include garbage collection and
non-cooperative
.BR userfaultfd (2).
See NOTES for some possible applications of
.BR MREMAP_DONTUNMAP .
.PP
If the memory segment specified by
.I old_address
@ -305,6 +304,33 @@ and the prototype for
did not allow for the
.I new_address
argument.
.\"
.SS MREMAP_DONTUNMAP use cases
Possible applications for
.BR MREMAP_DONTUNMAP
include:
.IP * 3
Non-cooperative
.BR userfaultfd (2):
an application can yank out a virtual address range using
.BR MREMAP_DONTUNMAP
and then employ a
.BR userfaultfd (2)
handler to handle the page faults that subsequently occur
as other threads in the process touch pages in the yanked range.
.IP *
Garbage collection:
.BR MREMAP_DONTUNMAP
can be used in conjunction with
.BR userfaultfd (2)
to implement garbage collection algorithms (e.g., in a Java virtual machine).
Such an implementation can be cheaper (and simpler)
than conventional garbage collection techniques that involve
marking pages with protection
.BR PROT_NONE
in conjunction with the of a
.BR SIGSEGV
handler to catch accesses to those pages.
.SH BUGS
Before Linux 4.14,
if