On Sun, Nov 13, 2016 at 07:51:02PM +0100, Nicolai Stange wrote: > Hi again, > > bad news: my previous analysis was completely wrong, c.f. below. > Good news (from my point of view): debugfs is correct, no fix needed for > it. > > Apologies for the confusion... > > > Nicolai Stange <nicstange@xxxxxxxxx> writes: > > > Greg KH <greg@xxxxxxxxx> writes: > > > >> On Mon, Oct 31, 2016 at 02:32:56PM -0400, Mike Marshall wrote: > >> > >>> But... really bad things happen if someone unloads the Orangefs > >>> module after my test program does the open and before the read > >>> starts. So I picked another debugfs-using-filesystem (f2fs) and > >>> pointed my tester-program at /sys/kernel/debug/f2fs/status, and > >>> the same bad thing happens there. > > > > [...] > > > >>> [ 1240.144316] Call Trace: > >>> [ 1240.144450] [<ffffffff8122907f>] __fput+0xdf/0x1d0 > >>> [ 1240.144704] [<ffffffff812291ae>] ____fput+0xe/0x10 > >>> [ 1240.144962] [<ffffffff810b97de>] task_work_run+0x8e/0xc0 > >>> [ 1240.145243] [<ffffffff8109b98e>] do_exit+0x2ae/0xae0 > > > > > > Thank you very much for this detailed report! > > > > At least for the .../f2fs/status file, your splat at fput() can be > > readily explained with the full proxy's releaser not being protected > > against file removals in any way. > > > > Partly this is on purpose, c.f. the comment in full_proxy_release(). > > > > However, I should have at least tried to acquire a reference to the > > owning module before accessing some static struct file_operations or > > even calling some ->release() within it. Meh. > > This is what I got wrong: debugfs does acquire the needed references > correctly (details below). For the case of f2fs' "status" file, the > file_operations ->owner is simply not set as it should have been, > i.e. to THIS_MODULE. Ah, good, care to make a f2fs patch to resolve the issue there? thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
