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Harding" To: Qian Cai Cc: akpm@linux-foundation.org, cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, tj@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] slab: fix a crash by reading /proc/slab_allocators Message-ID: <20190408050352.GA8889@eros.localdomain> References: <20190406225901.35465-1-cai@lca.pw> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190406225901.35465-1-cai@lca.pw> X-Mailer: Mutt 1.11.4 (2019-03-13) User-Agent: Mutt/1.11.4 (2019-03-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sat, Apr 06, 2019 at 06:59:01PM -0400, Qian Cai wrote: > The commit 510ded33e075 ("slab: implement slab_root_caches list") > changes the name of the list node within "struct kmem_cache" from > "list" to "root_caches_node", but leaks_show() still use the "list" > which causes a crash when reading /proc/slab_allocators. > > BUG: unable to handle kernel NULL pointer dereference at > 00000000000000aa > PGD 0 P4D 0 > Oops: 0000 [#1] SMP DEBUG_PAGEALLOC PTI > CPU: 3 PID: 5925 Comm: ldd Not tainted 5.1.0-rc3-mm1+ #6 > RIP: 0010:__lock_acquire.isra.14+0x4b4/0xa50 > Call Trace: > > lock_acquire+0xa3/0x180 > _raw_spin_lock+0x2f/0x40 > do_drain+0x61/0xc0 > flush_smp_call_function_queue+0x3a/0x110 > generic_smp_call_function_single_interrupt+0x13/0x2b > smp_call_function_interrupt+0x66/0x1a0 > call_function_interrupt+0xf/0x20 > > RIP: 0010:__tlb_remove_page_size+0x8c/0xe0 > zap_pte_range+0x39f/0xc80 > unmap_page_range+0x38a/0x550 > unmap_single_vma+0x7d/0xe0 > unmap_vmas+0xae/0xd0 > exit_mmap+0xae/0x190 > mmput+0x7a/0x150 > do_exit+0x2d9/0xd40 > do_group_exit+0x41/0xd0 > __x64_sys_exit_group+0x18/0x20 > do_syscall_64+0x68/0x381 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > Fixes: 510ded33e075 ("slab: implement slab_root_caches list") > Signed-off-by: Qian Cai > --- > mm/slab.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/slab.c b/mm/slab.c > index 46a6e084222b..9142ee992493 100644 > --- a/mm/slab.c > +++ b/mm/slab.c > @@ -4307,7 +4307,8 @@ static void show_symbol(struct seq_file *m, unsigned long address) > > static int leaks_show(struct seq_file *m, void *p) > { > - struct kmem_cache *cachep = list_entry(p, struct kmem_cache, list); > + struct kmem_cache *cachep = list_entry(p, struct kmem_cache, > + root_caches_node); > struct page *page; > struct kmem_cache_node *n; > const char *name; > -- > 2.17.2 (Apple Git-113) > For what its worth Reviewed-by: Tobin C. Harding thanks, Tobin.