Hi Jonathan, thanks for the patch! CCing Riku and Laurent.
On Mon, May 18, 2020 at 12:13:41PM -0600, Jonathan Marler wrote: > Been a few more days. Not sure how often I should be pinging. If this is > too much to ping every few days let me know. Is not too much, but next time is better to CC the maintainers. You can use 'scripts/get_maintainer.pl' to get the list of maintainers and reviewers. Please take a look at https://wiki.qemu.org/Contribute/SubmitAPatch > > On Fri, May 15, 2020 at 7:36 AM Jonathan Marler <johnnymar...@gmail.com> > wrote: > > > Been a couple weeks, checking to see if anyone has looked at this. > > > > On Sat, May 2, 2020 at 5:43 PM Jonathan Marler <johnnymar...@gmail.com> > > wrote: > > > >> FYI, I applied this patch to the qemu build that zig uses to run > >> non-native tests ( > >> https://github.com/ziglang/qemu-static/blob/master/patch/mremap-underflow.diff > >> ) > >> > >> After applying it, my new code that calls mremap now passes, > >> whereas before the fix I was getting a segfault. > >> > >> On Sat, May 2, 2020 at 10:12 AM Jonathan Marler <johnnymar...@gmail.com> > >> wrote: > >> > >>> Fixes: https://bugs.launchpad.net/bugs/1876373 should be "Buglink: https://bugs.launchpad.net/bugs/1876373" > >>> > >>> This code path in mmap occurs when a page size is decreased with > >>> mremap. When a section of pages is shrunk, qemu calls mmap_reserve on the > >>> pages that were released. However, it has the diff operation reversed, > >>> subtracting the larger old_size from the smaller new_size. Instead, it > >>> should be subtracting the smaller new_size from the larger old_size. You > >>> can also see in the previous line of the change that this mmap_reserve > >>> call > >>> only occurs when old_size > new_size. Please break the lines of the commit message (max 76 charactes per line): https://wiki.qemu.org/Contribute/SubmitAPatch#Write_a_meaningful_commit_message Thanks, Stefano > >>> > >>> Signed-off-by: Jonathan Marler <johnnymar...@gmail.com> > >>> --- > >>> linux-user/mmap.c | 2 +- > >>> 1 file changed, 1 insertion(+), 1 deletion(-) > >>> > >>> diff --git a/linux-user/mmap.c b/linux-user/mmap.c > >>> index e378033797..caab62909e 100644 > >>> --- a/linux-user/mmap.c > >>> +++ b/linux-user/mmap.c > >>> @@ -708,7 +708,7 @@ abi_long target_mremap(abi_ulong old_addr, abi_ulong > >>> old_size, > >>> if (prot == 0) { > >>> host_addr = mremap(g2h(old_addr), old_size, new_size, > >>> flags); > >>> if (host_addr != MAP_FAILED && reserved_va && old_size > > >>> new_size) { > >>> - mmap_reserve(old_addr + old_size, new_size - old_size); > >>> + mmap_reserve(old_addr + old_size, old_size - new_size); > >>> } > >>> } else { > >>> errno = ENOMEM; > >>> -- > >>> 2.23.1 > >>> > >>>