On Mon, Nov 16, 2020 at 10:17:20PM -0800, Hugh Dickins wrote: > On Mon, 16 Nov 2020, akpm@xxxxxxxxxxxxxxxxxxxx wrote: > > > > The patch titled > > Subject: mm/shmem: use kmem_cache_zalloc in shmem_alloc_inode() > > has been added to the -mm tree. Its filename is > > mm-shmem-use-kmem_cache_zalloc-in-shmem_alloc_inode.patch > > > > This patch should soon appear at > > https://ozlabs.org/~akpm/mmots/broken-out/mm-shmem-use-kmem_cache_zalloc-in-shmem_alloc_inode.patch > > and later at > > https://ozlabs.org/~akpm/mmotm/broken-out/mm-shmem-use-kmem_cache_zalloc-in-shmem_alloc_inode.patch > > > > Before you just go and hit "reply", please: > > a) Consider who else should be cc'ed > > b) Prefer to cc a suitable mailing list as well > > c) Ideally: find the original patch on the mailing list and do a > > reply-to-all to that, adding suitable additional cc's > > > > *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** > > > > The -mm tree is included into linux-next and is updated > > there every 3-4 working days > > > > ------------------------------------------------------ > > From: Hui Su <sh_def@xxxxxxx> > > Subject: mm/shmem: use kmem_cache_zalloc in shmem_alloc_inode() > > Andrew, Stephen, please revert this untested "cleanup" from your > trees a.s.a.p: it's a disaster for anyone using shmem/tmpfs. > > > > > in shmem_get_inode(): > > new_inode(); > > new_inode_pseudo(); > > alloc_inode(); > > ops->alloc_inode(); -> shmem_alloc_inode() > > kmem_cache_alloc(); > > > > memset(info, 0, (char *)inode - (char *)info); > > > > So use kmem_cache_zalloc() in shmem_alloc_inode(), > > and remove the memset in shmem_get_inode(). > > I could not follow that argument at all. The shmem_inode_cachep > uses a constructor, and the memset shown is of only a portion of > the whole inode. zeroing the entire inode quickly crashes the > kernel, after showing errors. > > (If you're lucky enough to have a readable display at that point: > I did not, but got on better with framebuffer than drm/i915; and > I wonder if there's a separate bug in that area too, because fixing > this shmem issue is not enough to get my drm/i915 rc4-mm1 booting.) > Sorry, I thought it was a small change before, so I forgot to test it. It's SO STUPID. I'm really sorry. > > > > Link: https://lkml.kernel.org/r/20201115174026.GA365412@rlk > > Signed-off-by: Hui Su <sh_def@xxxxxxx> > > NAK. Hui Su, please test your "cleanups" before sending them. > I will remember it, thanks. I have spent two evenings building a patch automated test platform using qemu and jenkins. > I'm sorry for being slow to respond, but the priority appeared > to be to get Matthew Wilcox's series running reliably, so I had not > got around to checking the less urgent shmem patches before they > slipped into mmotm - there may well be more that I want to NAK, > but this is the dangerous one. > > Thanks, > Hugh >
