Messages in this thread | | | Date | Thu, 19 Apr 2018 09:17:10 +0300 | From | Alexander Shishkin <> | Subject | Re: [PATCH 2/2] perf/core: fix bad use of igrab in kernel/event/core.c |
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On Tue, Apr 17, 2018 at 11:29:07PM -0700, Song Liu wrote: > As Miklos reported and suggested: > > This pattern repeats two times in trace_uprobe.c and in > kernel/events/core.c as well: > > ret = kern_path(filename, LOOKUP_FOLLOW, &path); > if (ret) > goto fail_address_parse; > > inode = igrab(d_inode(path.dentry)); > path_put(&path); > > And it's wrong. You can only hold a reference to the inode if you > have an active ref to the superblock as well (which is normally > through path.mnt) or holding s_umount.
Oops. I must have snatched it from the uprobe code without thinking.
> This way unmounting the containing filesystem while the tracepoint is > active will give you the "VFS: Busy inodes after unmount..." message > and a crash when the inode is finally put. > > Solution: store path instead of inode. > > This patch fixes the issue in kernel/event/core.c. > > NOTE: Based on my understanding, perf_addr_filter only supports intel_pt.
Coresight too, but that's probably even further away from what you have.
> However, my test system doesn't support address filtering (or I made a > mistake?). Therefore, I have NOT tested this patch.
Check /sys/devices/intel_pt/caps/num_address_ranges, if it's non-zero, it's supported.
> Could someone please help test it?
Yes:
Reviewed-and-tested-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
The subject line needs a little love to be more like other perf commits, but other than that, looks good.
Thanks!
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