Red Hat Bugzilla – Bug 435721
mmap may keep mmap_sem for a long time
Last modified: 2012-01-05 16:06:26 EST
Description of problem:
If a process locks its virtual address space in physical memory (either with
mlockall() or with the MAP_LOCKED flag of mmap), the time a call to mmap takes
increases with the size of the requested mapping and can take up to several tens
or hundreds of milliseconds. The whole time, mmap_sem is kept by the thread that
is mmaping thus preventing any other thread that also requires the mmap_sem in
the process from making progress.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
That is expected behaviour as the mmap call will have to install every page for such a mapping, therefore the time will increase linearly with the number of pages in it.
What other mmap_sem users in particular are held up by this?
There has been no recent activity on this issue. Is this still a problem?