On Sun, Sep 30, 2018 at 05:50:38AM -0700, Matthew Wilcox wrote: > On Sun, Sep 30, 2018 at 06:28:21PM +0800, zhong jiang wrote: > > From: Alexey Dobriyan <adobriyan@xxxxxxxxx> > > > > [ Upstream commit e5d9998f3e09359b372a037a6ac55ba235d95d57 ] > > > > /* > > * cpu_partial determined the maximum number of objects > > * kept in the per cpu partial lists of a processor. > > */ > > > > Can't be negative. > > > > I hit a real issue that it will result in a large number of memory leak. > > Becuase Freeing slabs are in interrupt context. So it can trigger this issue. > > put_cpu_partial can be interrupted more than once. > > due to a union struct of lru and pobjects in struct page, when other core handles > > page->lru list, for eaxmple, remove_partial in freeing slab code flow, It will > > result in pobjects being a negative value(0xdead0000). Therefore, a large number > > of slabs will be added to per_cpu partial list. > > > > I had posted the issue to community before. The detailed issue description is as follows. > > > > https://www.spinics.net/lists/kernel/msg2870979.html > > > > After applying the patch, The issue is fixed. So the patch is a effective bugfix. > > It should go into stable. > > > > Link: http://lkml.kernel.org/r/20180305200730.15812-15-adobriyan@xxxxxxxxx > > Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx> > > Acked-by: Christoph Lameter <cl@xxxxxxxxx> > > Hang on. Christoph acked the _original_ patch going into upstream. > When he reviewed this patch for _stable_ last week, he asked for more > investigation. Including this patch in stable is misleading. But the original patch has been in upstream for a long time now (it went into 4.17-rc1). If there was a real problem here, whouldn't it have been resolved already? And the patch in mainline has Christoph's ack... thanks, greg k-h
