• Dave Wysochanski's avatar
    cachefiles: Fix oops in trace_cachefiles_mark_buried due to NULL object · 6e9bfdcf
    Dave Wysochanski authored
    In cachefiles_mark_object_buried, the dentry in question may not have an
    owner, and thus our cachefiles_object pointer may be NULL when calling
    the tracepoint, in which case we will also not have a valid debug_id to
    print in the tracepoint.
    
    Check for NULL object in the tracepoint and if so, just set debug_id to
    MAX_UINT as was done in 2908f5e1 ("fscache: Add a cookie debug ID
    and use that in traces").
    
    This fixes the following oops:
    
        FS-Cache: Cache "mycache" added (type cachefiles)
        CacheFiles: File cache on vdc registered
        ...
        Workqueue: fscache_object fscache_object_work_func [fscache]
        RIP: 0010:trace_event_raw_event_cachefiles_mark_buried+0x4e/0xa0 [cachefiles]
        ....
        Call Trace:
         cachefiles_mark_object_buried+0xa5/0xb0 [cachefiles]
         cachefiles_bury_object+0x270/0x430 [cachefiles]
         cachefiles_walk_to_object+0x195/0x9c0 [cachefiles]
         cachefiles_lookup_object+0x5a/0xc0 [cachefiles]
         fscache_look_up_object+0xd7/0x160 [fscache]
         fscache_object_work_func+0xb2/0x340 [fscache]
         process_one_work+0x1f1/0x390
         worker_thread+0x53/0x3e0
         kthread+0x127/0x150
    
    Fixes: 2908f5e1 ("fscache: Add a cookie debug ID and use that in traces")
    Signed-off-by: default avatarDave Wysochanski <dwysocha@redhat.com>
    Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
    cc: linux-cachefs@redhat.com
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    6e9bfdcf
cachefiles.h 8.05 KB