Messages in this thread | | | Subject | Re: [PATCH] mm: cma: fix corruption cma_sysfs_alloc_pages_count | From | John Hubbard <> | Date | Wed, 24 Mar 2021 12:45:17 -0700 |
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On 3/24/21 12:20 PM, Minchan Kim wrote: > struct cma_stat's lifespan for cma_sysfs is different with > struct cma because kobject for sysfs requires dynamic object > while CMA is static object[1]. When CMA is initialized, > it couldn't use slab to allocate cma_stat since slab was not > initialized yet. Thus, it allocates the dynamic object > in subsys_initcall. > > However, the cma allocation can happens before subsys_initcall > then, it goes crash. > > Dmitry reported[2]: > > .. > [ 1.226190] [<c027762f>] (cma_sysfs_alloc_pages_count) from [<c027706f>] (cma_alloc+0x153/0x274) > [ 1.226720] [<c027706f>] (cma_alloc) from [<c01112ab>] (__alloc_from_contiguous+0x37/0x8c) > [ 1.227272] [<c01112ab>] (__alloc_from_contiguous) from [<c1104af9>] (atomic_pool_init+0x7b/0x126) > [ 1.233596] [<c1104af9>] (atomic_pool_init) from [<c0101d69>] (do_one_initcall+0x45/0x1e4) > [ 1.234188] [<c0101d69>] (do_one_initcall) from [<c1101141>] (kernel_init_freeable+0x157/0x1a6) > [ 1.234741] [<c1101141>] (kernel_init_freeable) from [<c0a27fd1>] (kernel_init+0xd/0xe0) > [ 1.235289] [<c0a27fd1>] (kernel_init) from [<c0100155>] (ret_from_fork+0x11/0x1c) > > This patch moves those statistic fields of cma_stat into struct cma > and introduces cma_kobject wrapper to follow kobject's rule. > > At the same time, it fixes other routines based on suggestions[3][4]. > > [1] https://lore.kernel.org/linux-mm/YCOAmXqt6dZkCQYs@kroah.com/ > [2] https://lore.kernel.org/linux-mm/fead70a2-4330-79ff-e79a-d8511eab1256@gmail.com/ > [3] https://lore.kernel.org/linux-mm/20210323195050.2577017-1-minchan@kernel.org/ > [4] https://lore.kernel.org/linux-mm/20210324010547.4134370-1-minchan@kernel.org/ > > Reported-by: Dmitry Osipenko <digetx@gmail.com> > Tested-by: Dmitry Osipenko <digetx@gmail.com> > Suggested-by: Dmitry Osipenko <digetx@gmail.com> > Suggested-by: John Hubbard <jhubbard@nvidia.com> > Suggested-by: Matthew Wilcox <willy@infradead.org> > Signed-off-by: Minchan Kim <minchan@kernel.org> > --- > I belive it's worth to have separate patch rather than replacing > original patch. It will also help to merge without conflict > since we already filed other patch based on it. > Strictly speaking, separating fix part and readbility part > in this patch would be better but it's gray to separate them > since most code in this patch was done while we were fixing > the bug. Since we don't release it yet, I hope it will work. > Otherwise, I can send a replacement patch inclucing all of > changes happend until now with gathering SoB.
If we still have a choice, we should not merge a patch that has a known serious problem, such as a crash. That's only done if the broken problematic patch has already been committed to a tree that doesn't allow rebasing, such as of course the main linux.git.
Here, I *think* it's just in linux-next and mmotm, so we still are allowed to fix the original patch.
thanks, -- John Hubbard NVIDIA
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