| Message ID | 20170411185235.GA32027@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Apr 11, 2017 at 12:52:35PM -0600, Ross Zwisler wrote: > On Tue, Apr 11, 2017 at 09:56:14AM -0400, Jeff Moyer wrote: > > Eryu Guan <eguan@redhat.com> writes: > > > > > On Mon, Apr 10, 2017 at 02:05:53PM +0800, Xiong Zhou wrote: > > >> Regression case that one can write to read-only > > >> file in a DAX mountpoint. > > >> > > >> Signed-off-by: Xiong Zhou <xzhou@redhat.com> > > >> --- > > >> > > >> v2: > > >> compile test programme manually in this test because default > > >> cc option -O2 prevents this issue reproduction; > > > > > > Hmm, this looks.. ugly to me :) Better to find out the exact reason that > > > prevents the bug from reproducing and update the c program accordingly. > > > > The compiler probably optimizes this bit out: > > > > + /* fault in the page */ > > + foo = *buf; > > Yep, verified this with objdump. You can prevent the compiler from > optimizing out this bit by making 'foo' volatile. Patch at the end of this > mail, and I also verified that this works with objdump. > > In my setup at least this test passes both with v4.10.0 (which does not > contain the fix we are testing for, and should fail) and with v4.10.3 (which > does contain the kernel fix, and should pass). > > So, I think the test still needs a little love. :) Umm...never mind, my testing was broken. I was accidentally testing with the upstream generic/422. :( Will retest tomorrow. -- To unsubscribe from this list: send the line "unsubscribe fstests" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Apr 11, 2017 at 04:45:42PM -0600, Ross Zwisler wrote: > On Tue, Apr 11, 2017 at 12:52:35PM -0600, Ross Zwisler wrote: > > On Tue, Apr 11, 2017 at 09:56:14AM -0400, Jeff Moyer wrote: > > > Eryu Guan <eguan@redhat.com> writes: > > > > > > > On Mon, Apr 10, 2017 at 02:05:53PM +0800, Xiong Zhou wrote: > > > >> Regression case that one can write to read-only > > > >> file in a DAX mountpoint. > > > >> > > > >> Signed-off-by: Xiong Zhou <xzhou@redhat.com> > > > >> --- > > > >> > > > >> v2: > > > >> compile test programme manually in this test because default > > > >> cc option -O2 prevents this issue reproduction; > > > > > > > > Hmm, this looks.. ugly to me :) Better to find out the exact reason that > > > > prevents the bug from reproducing and update the c program accordingly. > > > > > > The compiler probably optimizes this bit out: > > > > > > + /* fault in the page */ > > > + foo = *buf; > > > > Yep, verified this with objdump. You can prevent the compiler from > > optimizing out this bit by making 'foo' volatile. Patch at the end of this > > mail, and I also verified that this works with objdump. > > > > In my setup at least this test passes both with v4.10.0 (which does not > > contain the fix we are testing for, and should fail) and with v4.10.3 (which > > does contain the kernel fix, and should pass). > > > > So, I think the test still needs a little love. :) > > Umm...never mind, my testing was broken. I was accidentally testing with the > upstream generic/422. :( Will retest tomorrow. Thank you very much Ross, your patch is working fine. -- To unsubscribe from this list: send the line "unsubscribe fstests" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/src/t_mmap_write_ro.c b/src/t_mmap_write_ro.c index cce6e0d..3960815 100644 --- a/src/t_mmap_write_ro.c +++ b/src/t_mmap_write_ro.c @@ -11,7 +11,8 @@ int main(int argc, char **argv) { int fd, pfd, ret; - char *buf, foo; + char *buf; + volatile char foo; int pagesize = getpagesize(); if (argc < 2) {