From: Song Liu songliubraving@fb.com
commit 9511bce9fe8e5e6c0f923c09243a713eba560141 upstream
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.
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.
Reviewed-and-tested-by: Alexander Shishkin alexander.shishkin@linux.intel.com Reported-by: Miklos Szeredi miklos@szeredi.hu Signed-off-by: Song Liu songliubraving@fb.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Cc: kernel-team@fb.com Cc: Alexander Shishkin alexander.shishkin@linux.intel.com Cc: Arnaldo Carvalho de Melo acme@redhat.com Cc: Jiri Olsa jolsa@redhat.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Cc: Stephane Eranian eranian@google.com Cc: Thomas Gleixner tglx@linutronix.de Cc: Vince Weaver vincent.weaver@maine.edu Fixes: 375637bc5249 ("perf/core: Introduce address range filtering") Link: http://lkml.kernel.org/r/20180418062907.3210386-2-songliubraving@fb.com Signed-off-by: Ingo Molnar mingo@kernel.org [sudip: Backported to 4.9: use file_inode()] Signed-off-by: Sudip Mukherjee sudipm.mukherjee@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/events/intel/pt.c | 4 ++-- include/linux/perf_event.h | 2 +- kernel/events/core.c | 21 +++++++++------------ 3 files changed, 12 insertions(+), 15 deletions(-)
--- a/arch/x86/events/intel/pt.c +++ b/arch/x86/events/intel/pt.c @@ -1117,7 +1117,7 @@ static int pt_event_addr_filters_validat if (!filter->range || !filter->size) return -EOPNOTSUPP;
- if (!filter->inode) { + if (!filter->path.dentry) { if (!valid_kernel_ip(filter->offset)) return -EINVAL;
@@ -1144,7 +1144,7 @@ static void pt_event_addr_filters_sync(s return;
list_for_each_entry(filter, &head->list, entry) { - if (filter->inode && !offs[range]) { + if (filter->path.dentry && !offs[range]) { msr_a = msr_b = 0; } else { /* apply the offset */ --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -475,7 +475,7 @@ struct pmu { */ struct perf_addr_filter { struct list_head entry; - struct inode *inode; + struct path path; unsigned long offset; unsigned long size; unsigned int range : 1, --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6271,7 +6271,7 @@ static void perf_event_addr_filters_exec
raw_spin_lock_irqsave(&ifh->lock, flags); list_for_each_entry(filter, &ifh->list, entry) { - if (filter->inode) { + if (filter->path.dentry) { event->addr_filters_offs[count] = 0; restart++; } @@ -6814,7 +6814,7 @@ static bool perf_addr_filter_match(struc struct file *file, unsigned long offset, unsigned long size) { - if (filter->inode != file->f_inode) + if (d_inode(filter->path.dentry) != file_inode(file)) return false;
if (filter->offset > offset + size) @@ -8028,8 +8028,7 @@ static void free_filters_list(struct lis struct perf_addr_filter *filter, *iter;
list_for_each_entry_safe(filter, iter, filters, entry) { - if (filter->inode) - iput(filter->inode); + path_put(&filter->path); list_del(&filter->entry); kfree(filter); } @@ -8123,7 +8122,7 @@ static void perf_event_addr_filters_appl * Adjust base offset if the filter is associated to a binary * that needs to be mapped: */ - if (filter->inode) + if (filter->path.dentry) event->addr_filters_offs[count] = perf_addr_filter_apply(filter, mm);
@@ -8196,7 +8195,6 @@ perf_event_parse_addr_filter(struct perf { struct perf_addr_filter *filter = NULL; char *start, *orig, *filename = NULL; - struct path path; substring_t args[MAX_OPT_ARGS]; int state = IF_STATE_ACTION, token; unsigned int kernel = 0; @@ -8287,19 +8285,18 @@ perf_event_parse_addr_filter(struct perf goto fail;
/* look up the path and grab its inode */ - ret = kern_path(filename, LOOKUP_FOLLOW, &path); + ret = kern_path(filename, LOOKUP_FOLLOW, + &filter->path); if (ret) goto fail_free_name;
- filter->inode = igrab(d_inode(path.dentry)); - path_put(&path); kfree(filename); filename = NULL;
ret = -EINVAL; - if (!filter->inode || - !S_ISREG(filter->inode->i_mode)) - /* free_filters_list() will iput() */ + if (!filter->path.dentry || + !S_ISREG(d_inode(filter->path.dentry) + ->i_mode)) goto fail; }