Messages in this thread Patch in this message | | | Date | Tue, 7 Nov 2017 11:51:25 -0800 | From | Andrei Vagin <> | Subject | Re: lost path_put in perf_fill_ns_link_info |
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On Tue, Nov 07, 2017 at 11:03:18AM -0800, Andrei Vagin wrote: > Hi Vasily and all, > > The patch looks correct for me. I tried to reproduce this issue and > checked that this patch fixes it. Bellow you can find my test program > and a command line to run it. The problem still exists even with this patch. > > $ cat test.c > #define _GNU_SOURCE > #include <sched.h> > > int main(int argc, char **argv) > { > while (1) > unshare(CLONE_NEWUTS); > return 0; > } > > $ gcc -o test_unshare test.c > $ for i in `seq 10000`; do perf trace -o log unshare -u true; done & > [5] 28766 > $ for i in `seq 10000`; do perf trace -o log unshare -u true; done & > [6] 28840 > > $ echo 3 > /proc/sys/vm/drop_caches | cat /proc/slabinfo | grep dentry > dentry 74848 78660 224 18 1 : tunables 0 0 0 : slabdata 4370 4370 0 > > $ sleep 10 > $ echo 3 > /proc/sys/vm/drop_caches | cat /proc/slabinfo | grep dentry > dentry 75145 79002 224 18 1 : tunables 0 0 0 : slabdata 4389 4389 0 > > $ sleep 10 > $ echo 3 > /proc/sys/vm/drop_caches | cat /proc/slabinfo | grep dentry > dentry 75921 79776 224 18 1 : tunables 0 0 0 : slabdata 4432 4432 0
Actually here is another issue, and it is reproduced by another script:
for i in `seq 10000`; do perf trace -o /dev/null unshare -u true; done &
And it is due to files what perf creates in /tmp
//tmp/perf-vdso.so-84wDCZ //tmp/perf-vdso.so-YDfUuX //tmp/perf-vdso.so-KkTBfU //tmp/perf-vdso.so-srXfvU //tmp/perf-vdso.so-QrPscR //tmp/perf-vdso.so-wlxIZO //tmp/perf-vdso.so-ur4fBP //tmp/perf-vdso.so-gBMExN //tmp/perf-vdso.so-6sCehK //tmp/perf-vdso.so-cZ4GDK //tmp/perf-vdso.so-ImQLoH //tmp/perf-vdso.so-y4rMuF //tmp/perf-vdso.so-Wx1qIG //tmp/perf-vdso.so-g5mYOD ...
Do we really need all these files? They all are identical.
[root@fc24 ~]# diff -up /tmp/perf-vdso.so-fnVcRz /tmp/perf-vdso.so-FQGYzh [root@fc24 ~]# echo $? 0 > $ git log --pretty=oneline | head -n 2 > c83bceb10b36cef895def4b2dfe0aff6ca7c9784 lost path_put in perf_fill_ns_link_info > 8b82a8a7ab53ee1a065ac69c835737a701f46b2e Add linux-next specific files for 20171107 > > Thanks, > Andrei > > On Mon, Nov 06, 2017 at 09:22:18AM +0300, Vasily Averin wrote: > > Fixes: commit e422267322cd ("perf: Add PERF_RECORD_NAMESPACES to include namespaces related info") > > Signed-off-by: Vasily Averin <vvs@virtuozzo.com> > > --- > > kernel/events/core.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/kernel/events/core.c b/kernel/events/core.c > > index 10cdb9c..ab5ac84 100644 > > --- a/kernel/events/core.c > > +++ b/kernel/events/core.c > > @@ -6756,6 +6756,7 @@ static void perf_fill_ns_link_info(struct perf_ns_link_info *ns_link_info, > > ns_inode = ns_path.dentry->d_inode; > > ns_link_info->dev = new_encode_dev(ns_inode->i_sb->s_dev); > > ns_link_info->ino = ns_inode->i_ino; > > + path_put(&ns_path); > > } > > } > >
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