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Wed, 17 Sep 2025 08:03:26 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id r/GZFk5rymgYfQAAD6G6ig (envelope-from ); Wed, 17 Sep 2025 08:03:26 +0000 Message-ID: Date: Wed, 17 Sep 2025 10:03:26 +0200 Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [linux-next:master] [slab] db93cdd664: BUG:kernel_NULL_pointer_dereference,address Content-Language: en-US To: kernel test robot , Alexei Starovoitov , Harry Yoo Cc: oe-lkp@lists.linux.dev, lkp@intel.com, kasan-dev@googlegroups.com, cgroups@vger.kernel.org, linux-mm@kvack.org References: <202509171214.912d5ac-lkp@intel.com> From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSBWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmN6PsLBlAQTAQoAPgIbAwULCQgHAwUVCgkICwUWAgMBAAIe AQIXgBYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJnyBr8BQka0IFQAAoJECJPp+fMgqZkqmMQ AIbGN95ptUMUvo6aAdhxaOCHXp1DfIBuIOK/zpx8ylY4pOwu3GRe4dQ8u4XS9gaZ96Gj4bC+ jwWcSmn+TjtKW3rH1dRKopvC07tSJIGGVyw7ieV/5cbFffA8NL0ILowzVg8w1ipnz1VTkWDr 2zcfslxJsJ6vhXw5/npcY0ldeC1E8f6UUoa4eyoskd70vO0wOAoGd02ZkJoox3F5ODM0kjHu Y97VLOa3GG66lh+ZEelVZEujHfKceCw9G3PMvEzyLFbXvSOigZQMdKzQ8D/OChwqig8wFBmV QCPS4yDdmZP3oeDHRjJ9jvMUKoYODiNKsl2F+xXwyRM2qoKRqFlhCn4usVd1+wmv9iLV8nPs 2Db1ZIa49fJet3Sk3PN4bV1rAPuWvtbuTBN39Q/6MgkLTYHb84HyFKw14Rqe5YorrBLbF3rl M51Dpf6Egu1yTJDHCTEwePWug4XI11FT8lK0LNnHNpbhTCYRjX73iWOnFraJNcURld1jL1nV r/LRD+/e2gNtSTPK0Qkon6HcOBZnxRoqtazTU6YQRmGlT0v+rukj/cn5sToYibWLn+RoV1CE Qj6tApOiHBkpEsCzHGu+iDQ1WT0Idtdynst738f/uCeCMkdRu4WMZjteQaqvARFwCy3P/jpK uvzMtves5HvZw33ZwOtMCgbpce00DaET4y/UzsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZ8gcVAUJFhTonwAKCRAiT6fnzIKmZLY8D/9uo3Ut9yi2YCuASWxr7QQZ lJCViArjymbxYB5NdOeC50/0gnhK4pgdHlE2MdwF6o34x7TPFGpjNFvycZqccSQPJ/gibwNA zx3q9vJT4Vw+YbiyS53iSBLXMweeVV1Jd9IjAoL+EqB0cbxoFXvnjkvP1foiiF5r73jCd4PR rD+GoX5BZ7AZmFYmuJYBm28STM2NA6LhT0X+2su16f/HtummENKcMwom0hNu3MBNPUOrujtW khQrWcJNAAsy4yMoJ2Lw51T/5X5Hc7jQ9da9fyqu+phqlVtn70qpPvgWy4HRhr25fCAEXZDp xG4RNmTm+pqorHOqhBkI7wA7P/nyPo7ZEc3L+ZkQ37u0nlOyrjbNUniPGxPxv1imVq8IyycG AN5FaFxtiELK22gvudghLJaDiRBhn8/AhXc642/Z/yIpizE2xG4KU4AXzb6C+o7LX/WmmsWP Ly6jamSg6tvrdo4/e87lUedEqCtrp2o1xpn5zongf6cQkaLZKQcBQnPmgHO5OG8+50u88D9I rywqgzTUhHFKKF6/9L/lYtrNcHU8Z6Y4Ju/MLUiNYkmtrGIMnkjKCiRqlRrZE/v5YFHbayRD dJKXobXTtCBYpLJM4ZYRpGZXne/FAtWNe4KbNJJqxMvrTOrnIatPj8NhBVI0RSJRsbilh6TE m6M14QORSWTLRg== In-Reply-To: <202509171214.912d5ac-lkp@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spam-Level: X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-0.998]; MIME_GOOD(-0.10)[text/plain]; RCVD_VIA_SMTP_AUTH(0.00)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; RCPT_COUNT_SEVEN(0.00)[8]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_TLS_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; DBL_BLOCKED_OPENRESOLVER(0.00)[intel.com:email,imap1.dmz-prg2.suse.org:helo] X-Spam-Flag: NO X-Spam-Score: -4.30 On 9/17/25 07:01, kernel test robot wrote: > > > Hello, > > kernel test robot noticed "BUG:kernel_NULL_pointer_dereference,address" on: > > commit: db93cdd664fa02de9be883dd29343b21d8fc790f ("slab: Introduce kmalloc_nolock() and kfree_nolock().") > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master > > in testcase: boot > > config: i386-randconfig-062-20250913 > compiler: clang-20 > test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G > > (please refer to attached dmesg/kmsg for entire log/backtrace) > > > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > the same patch/commit), kindly add following tags > | Reported-by: kernel test robot > | Closes: https://lore.kernel.org/oe-lkp/202509171214.912d5ac-lkp@intel.com > > > [ 7.101117][ T0] BUG: kernel NULL pointer dereference, address: 00000010 > [ 7.102290][ T0] #PF: supervisor read access in kernel mode > [ 7.103219][ T0] #PF: error_code(0x0000) - not-present page > [ 7.104161][ T0] *pde = 00000000 > [ 7.104762][ T0] Thread overran stack, or stack corrupted Note this. > [ 7.105726][ T0] Oops: Oops: 0000 [#1] > [ 7.106410][ T0] CPU: 0 UID: 0 PID: 0 Comm: swapper Tainted: G T 6.17.0-rc3-00014-gdb93cdd664fa #1 NONE 40eff3b43e4f0000b061f2e660abd0b2911f31b1 > [ 7.108712][ T0] Tainted: [T]=RANDSTRUCT > [ 7.109368][ T0] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 > [ 7.110952][ T0] EIP: kmalloc_nolock_noprof (mm/slub.c:5607) That's here. if (!(s->flags & __CMPXCHG_DOUBLE) && !kmem_cache_debug(s)) dmesg already contains line "SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1" so all kmem caches are fully initialized, so doesn't look like a bootstrap issue. Probably it's due to the stack overflow and not actual bug on this line. Because of that it's also unable to print the backtrace. But the only kmallock_nolock usage for now is in slub itself, alloc_slab_obj_exts(): /* Prevent recursive extension vector allocation */ gfp |= __GFP_NO_OBJ_EXT; if (unlikely(!allow_spin)) { size_t sz = objects * sizeof(struct slabobj_ext); vec = kmalloc_nolock(sz, __GFP_ZERO, slab_nid(slab)); } else { vec = kcalloc_node(objects, sizeof(struct slabobj_ext), gfp, slab_nid(slab)); } Prevent recursive... hm? And we had stack overflow? Also .config has CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT=y So, this? diff --git a/mm/slub.c b/mm/slub.c index 837ee037abb5..c4f17ac6e4b6 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2092,7 +2092,8 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s, if (unlikely(!allow_spin)) { size_t sz = objects * sizeof(struct slabobj_ext); - vec = kmalloc_nolock(sz, __GFP_ZERO, slab_nid(slab)); + vec = kmalloc_nolock(sz, __GFP_ZERO | __GFP_NO_OBJ_EXT, + slab_nid(slab)); } else { vec = kcalloc_node(objects, sizeof(struct slabobj_ext), gfp, slab_nid(slab)); @@ -5591,7 +5592,8 @@ void *kmalloc_nolock_noprof(size_t size, gfp_t gfp_flags, int node) bool can_retry = true; void *ret = ERR_PTR(-EBUSY); - VM_WARN_ON_ONCE(gfp_flags & ~(__GFP_ACCOUNT | __GFP_ZERO)); + VM_WARN_ON_ONCE(gfp_flags & ~(__GFP_ACCOUNT | __GFP_ZERO | + __GFP_NO_OBJ_EXT)); if (unlikely(!size)) return ZERO_SIZE_PTR;