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userfaultfd.2: Minor fixes to Prakash Sangappa's patch 

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Michael Kerrisk 2017-10-18 10:37:29 +02:00
parent 1df2779d72
commit e81833beb2
1 changed files with 13 additions and 10 deletions
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23
man2/userfaultfd.2
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@ -172,28 +172,31 @@ or
.BR ioctl (2)
operations to resolve the page fault.
.PP
Starting from Linux 4.14, if application sets
Starting from Linux 4.14, if the application sets the
.B UFFD_FEATURE_SIGBUS
feature bit using
feature bit using the
.B UFFDIO_API
.BR ioctl (2),
no page fault notification will be forwarded to
the user-space, instead a
no page-fault notification will be forwarded to user space.
Instead a
.B SIGBUS
signal is delivered to the faulting process. With this feature,
userfaultfd can be used for robustness purpose to simply catch
signal is delivered to the faulting process.
With this feature,
userfaultfd can be used for robustness purposes to simply catch
any access to areas within the registered address range that do not
have pages allocated, without having to listen to userfaultfd events.
No userfaultfd monitor will be required for dealing with such memory
accesses. For example, this feature can be useful for applications that
accesses.
For example, this feature can be useful for applications that
want to prevent the kernel from automatically allocating pages and filling
holes in sparse files when the hole is accessed thru mapped address.
holes in sparse files when the hole is accessed through a memory mapping.
.PP
The
.B UFFD_FEATURE_SIGBUS
feature is implicitly inherited through fork() if used in combination with
feature is implicitly inherited through
.BR fork (2)
if used in combination with
.BR UFFD_FEATURE_FORK .
.PP
Details of the various
.BR ioctl (2)