On Fri, Sep 4, 2009 at 1:25 AM, Catalin Marinas<catalin.marinas@xxxxxxx> wrote: > On Fri, 2009-09-04 at 07:04 +0200, Johannes Berg wrote: >> On Thu, 2009-09-03 at 13:43 -0700, Luis R. Rodriguez wrote: >> > On Thu, Sep 03, 2009 at 11:17:17AM -0700, Johannes Berg wrote: >> > > On Thu, 2009-09-03 at 11:13 -0700, Luis R. Rodriguez wrote: >> > > >> > > > What I meant is it gobbles it up and spits another thing out. When it >> > > > gobbles it up the routine then uses kref_put(). >> > > > >> > > > > Why can it not track this? >> > > > >> > > > It probably can, just not sure if it follows kref_put(), I was under >> > > > the impression here it doesn't and because of it we were getting false >> > > > positives. Catalin, can you confirm? >> > > >> > > Ah I'd think that if it can't track it then that's because we use a >> > > pointer to the middle of the struct to keep track of it much of the >> > > time. >> > >> > So you agree with the patch but not the commit log entry? >> >> I'm not sure -- I think kmemleak should be able to figure it out, and if >> you were using IBSS then we actually have a leak that we need to plug, >> but otherwise I'd prefer to get some more input from Catalin first. > > First of all, kmemleak_ignore() is not the right function to mark a > false positive as it completely ignores an object even though it may > have pointers to others. The kmemleak_not_leak() function should be > used. However, there are only two places in the kernel where this was > actually needed (one of them is a real leak but we ignore it as it makes > the code more complicated). > > So, I think we should try to figure out why kmemleak reports it. There > are a few common cases: > 1. transient false positive - this should disappear after a few > scans > 2. a pointer leading to the reported object is stored in an area of > memory not scanned by kmemleak - most commonly pages allocated > explicitly (alloc_pages etc.) as kmemleak doesn't track these. > The preferred solution is to inform kmemleak about such page > (kmemleak_alloc/kmemleak_free) rather than marking the false > positive > 3. a pointer leading to the reported object isn't actually pointing > to anywhere inside the structure (i.e. using the physical > address). Here we would use kmemleak_not_leak() John please revert this merged patch (b563f91105758c35d7cd4589992198b9da52d579) on wireless-testing as we'd like to investigate further why we get this. BTW I should not I got this kmemleak report after using the clear command by painting objects black. I'll test it now with your suggested changes. Luis -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
