On Mon, Oct 28, 2013 at 11:30 AM, Veaceslav Falico <vfalico@xxxxxxxxxx> wrote: > On Mon, Oct 28, 2013 at 11:23:41AM -0600, Bjorn Helgaas wrote: >> >> [+cc Veaceslav] >> >> On Sun, Oct 27, 2013 at 3:24 PM, Greg Kroah-Hartman >> <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: >>> >>> On Sun, Oct 27, 2013 at 09:13:29PM +0000, Linus Torvalds wrote: >>>> >>>> .. and one more case of freeing a delayed work object (likely a kobject >>>> again): >>>> >>>> This time it looks like it's in the PCI layer, freeing the msi irq >>>> information. >>>> >>>> It looks like that code simply does >>>> >>>> kobject_del(&entry->kobj); >>>> kobject_put(&entry->kobj); >>>> list_del(&entry->list); >>>> kfree(entry); >>>> >>>> and the problem is that the "entry->kobj" may have *other* references >>>> to it, thanks to people accessing it through /sys, so despite doing a >>>> kojbect_del/kobject_put(), it's not at all ok to then do a "kfree()" >>>> on it. The embedded kobj might still be in use. >>>> >>>> Afaik, that code should do the kfree() on the kobject in the _release_ >>>> method, not synchronously like that. >>>> >>>> We already have a msi_kobj_release(), I'm wondering why that doesn't >>>> do the kfree(). >>>> >>>> Bjorn? Yinghai? Greg, comments about that msi kobj usage? >>> >>> >>> Ick, it really should be doing a kfree() in the release only. Bjorn has >>> had a bunch of changes in this area recently, perhaps they are in >>> linux-next waiting for 3.13, and I've talked to him about getting rid of >>> all of the kobjects for msi files, as I don't think it's needed at all. >> >> >> IIRC, you said you might take a look at converting this to attributes >> on the train back home, so I haven't looked into it myself :) >> >>> Bjorn, don't you have a fix for this problem already done somewhere? >> >> >> Yep, this is clearly wrong, and Veaceslav has a patch that moves the >> kfree() to the release function. I've been waiting for a consolidated >> repost of all his MSI-related fixes, but maybe he's been waiting for >> *me*. > > > https://lkml.org/lkml/2013/10/9/170 > > My patchset is ready to be applied, in its v2 state. > > Except that the bits with kobject_del() (theoretical race) - which are done > in your patch "kobject: remove kset from sysfs immediately in > kset_unregister()", though I didn't see it accepted. > > Should I re-send the patchset? Can you please repost it? That will be easier for me than digging individual messages out of the archives. Thanks, and sorry for my confusion. Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
