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Shutemov" , Muchun Song CC: , , , , , , , References: <20241014032336.482088-1-chenridong@huaweicloud.com> Content-Language: en-US From: chenridong In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.109.79] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemd100013.china.huawei.com (7.221.188.163) X-Rspamd-Queue-Id: C037040004 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: g7puyakax96m1nusddinendfmy3uyo5n X-HE-Tag: 1729041929-227435 X-HE-Meta: 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 po9LF6XV ZJnfGZKHUMmaWTAqYzaRYFMCKJsoABERxARSnqJoVxaStBdMMyLw0OQFkx99ft+4tVd0y2UtIeUPIYjEsMh58lFhhR/I23bGSyXJrau3MUjhKX1+MhVcupEb5FHafA3VKEnTpIkS7X6CoYvI77LLdDNkyffjccE0kXQhcF92+Me8h4s02+o4Kbq4V7rW7J7iAcrr8skUE359rLlDRbkfiAC7hrtwmojLojM8O/+uEKvUOJPoUMqZetWVRbQ== 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: List-Subscribe: List-Unsubscribe: On 2024/10/15 14:55, Anshuman Khandual wrote: > > > On 10/14/24 16:59, Kirill A. Shutemov wrote: >> On Mon, Oct 14, 2024 at 03:23:36AM +0000, Chen Ridong wrote: >>> From: Chen Ridong >>> >>> A memleak was found as bellow: >>> >>> unreferenced object 0xffff8881010d2a80 (size 32): >>> comm "mkdir", pid 1559, jiffies 4294932666 >>> hex dump (first 32 bytes): >>> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ >>> 40 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 @............... >>> backtrace (crc 2e7ef6fa): >>> [] __kmalloc_node_noprof+0x394/0x470 >>> [] alloc_shrinker_info+0x7b/0x1a0 >>> [] mem_cgroup_css_online+0x11a/0x3b0 >>> [] online_css+0x29/0xa0 >>> [] cgroup_apply_control_enable+0x20d/0x360 >>> [] cgroup_mkdir+0x168/0x5f0 >>> [] kernfs_iop_mkdir+0x5e/0x90 >>> [] vfs_mkdir+0x144/0x220 >>> [] do_mkdirat+0x87/0x130 >>> [] __x64_sys_mkdir+0x49/0x70 >>> [] do_syscall_64+0x68/0x140 >>> [] entry_SYSCALL_64_after_hwframe+0x76/0x7e >>> >>> In the alloc_shrinker_info function, when shrinker_unit_alloc return >>> err, the info won't be freed. Just fix it. >>> >>> Fixes: 307bececcd12 ("mm: shrinker: add a secondary array for shrinker_info::{map, nr_deferred}") >>> Signed-off-by: Chen Ridong >>> --- >>> mm/shrinker.c | 1 + >>> 1 file changed, 1 insertion(+) >>> >>> diff --git a/mm/shrinker.c b/mm/shrinker.c >>> index dc5d2a6fcfc4..92270413190d 100644 >>> --- a/mm/shrinker.c >>> +++ b/mm/shrinker.c >>> @@ -97,6 +97,7 @@ int alloc_shrinker_info(struct mem_cgroup *memcg) >>> >>> err: >>> mutex_unlock(&shrinker_mutex); >>> + kvfree(info); >>> free_shrinker_info(memcg); >>> return -ENOMEM; >>> } >> >> NAK. If in the future there going to one more error case after >> rcu_assign_pointer() we will end up with double free. >> >> This should be safer: >> >> diff --git a/mm/shrinker.c b/mm/shrinker.c >> index dc5d2a6fcfc4..763fd556bc7d 100644 >> --- a/mm/shrinker.c >> +++ b/mm/shrinker.c >> @@ -87,8 +87,10 @@ int alloc_shrinker_info(struct mem_cgroup *memcg) >> if (!info) >> goto err; >> info->map_nr_max = shrinker_nr_max; >> - if (shrinker_unit_alloc(info, NULL, nid)) >> + if (shrinker_unit_alloc(info, NULL, nid)) { >> + kvfree(info); >> goto err; >> + } >> rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_info, info); >> } >> mutex_unlock(&shrinker_mutex); > > Agreed, this is what I mentioned earlier as well. > > ------------------------------------------------------------------ > I guess kvfree() should be called just after shrinker_unit_alloc() > fails but before calling into "goto err" > ------------------------------------------------------------------ > After discussion, it seems that v1 is acceptable. Hi, Muchun, do you have any other opinions? Best regards, Ridong