The commit 7197fb4058bcb68986bae2bb2c04d6370f3e7218 ("util/mmap-alloc:
fix hugetlb support on ppc64") fixed Huge TLB mappings on ppc64.
However, we still need to consider the underlying huge page size
during munmap() because it requires that both address and length be a
multiple of the underlying huge page size for Huge TLB mappings.
Quote from "Huge page (Huge TLB) mappings" paragraph under NOTES
section of the munmap(2) manual:
"For munmap(), addr and length must both be a multiple of the
underlying huge page size."
On ppc64, the munmap() in qemu_ram_munmap() does not work for Huge TLB
mappings because the mapped segment can be aligned with the underlying
huge page size, not aligned with the native system page size, as
returned by getpagesize().
This has the side effect of not releasing huge pages back to the pool
after a hugetlbfs file-backed memory device is hot-unplugged.
This patch fixes the situation in qemu_ram_mmap() and
qemu_ram_munmap() by considering the underlying page size on ppc64.
After this patch, memory hot-unplug releases huge pages back to the
pool.
Fixes: 7197fb4058bcb68986bae2bb2c04d6370f3e7218
Backports commit 53adb9d43e1abba187387a51f238e878e934c647 from qemu
Unfold parts of qemu_ram_mmap() for the sake of understanding, moving
declarations to the top, and keeping architecture-specifics in the
ifdef-else blocks. No changes in the function behaviour.
Give ptr and ptr1 meaningful names:
ptr -> guardptr : pointer to the PROT_NONE guard region
ptr1 -> ptr : pointer to the mapped memory returned to caller
Backports commit 2044c3e7116eeac0449dcb4a4130cc8f8b9310da from qemu
1st mmap returns *ptr* which aligns to host page size,
| size + align |
------------------------------------------
ptr
input param *align* could be 1M, or 2M, or host page size. After
QEMU_ALIGN_UP, offset will >= 0
2nd mmap use flag MAP_FIXED, then it return ptr+offset, or else fail.
If it success, then we will have something like:
| offset | size |
--------------------------------------
ptr ptr1
*ptr1* is what we really want to return, it equals ptr+offset.
Backports commit 6e4c890e15b23f078650499fbde11760b8eccf10 from qemu
Tracked down with an ugly, brittle and probably buggy Perl script.
Also move includes converted to <...> up so they get included before
ours where that's obviously okay.
Backports commit a9c94277f07d19d3eb14f199c3e93491aa3eae0e from qemu
Clean up includes so that osdep.h is included first and headers
which it implies are not included manually.
This commit was created with scripts/clean-includes.
Backports commit aafd758410015e08b1aa8964d739ba8587ce58dc from qemu
Anonymous and file-backed RAM allocation are now almost exactly the same.
Reduce code duplication by moving RAM mmap code out of oslib-posix.c and
exec.c.
Backports commit 794e8f301a17953efa78ab7538019ec43c59e82a from qemu
