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Fri, 18 Jun 2021 06:15:27 -0700 (PDT) MIME-Version: 1.0 References: <1624019875-611-1-git-send-email-faiyazm@codeaurora.org> In-Reply-To: <1624019875-611-1-git-send-email-faiyazm@codeaurora.org> From: Andy Shevchenko Date: Fri, 18 Jun 2021 16:15:11 +0300 Message-ID: Subject: Re: [PATCH v1] mm: slub: fix the leak of alloc/free traces debugfs interface To: Faiyaz Mohammed Cc: Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Vlastimil Babka , linux-mm , Linux Kernel Mailing List , Greg KH , glittao@gmail.com, vinmenon@codeaurora.org, Catalin Marinas , Alexander Viro , Linux FS Devel Content-Type: text/plain; charset="UTF-8" Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=gmail.com header.s=20161025 header.b=AKX0kcMM; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf01.hostedemail.com: domain of andyshevchenko@gmail.com designates 209.85.215.180 as permitted sender) smtp.mailfrom=andyshevchenko@gmail.com X-Rspamd-Server: rspam02 X-Stat-Signature: epgmp6e575hkk1odq7pfzzxuzr59znco X-Rspamd-Queue-Id: D4C11500170B X-HE-Tag: 1624022128-943532 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 Fri, Jun 18, 2021 at 3:38 PM Faiyaz Mohammed wrote: > > fix the leak of alloc/free traces debugfs interface, reported Fix > by kmemleak like below, > > unreferenced object 0xffff00091ae1b540 (size 64): > comm "lsbug", pid 1607, jiffies 4294958291 (age 1476.340s) > hex dump (first 32 bytes): > 02 00 00 00 00 00 00 00 6b 6b 6b 6b 6b 6b 6b 6b ........kkkkkkkk > 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk > backtrace: > [] slab_post_alloc_hook+0xa0/0x418 > [] kmem_cache_alloc_trace+0x1e4/0x378 > [] slab_debugfs_start+0x30/0x50 > slab_debugfs_start at mm/slub.c:5831 > [] seq_read_iter+0x214/0xd50 > [] seq_read+0x28c/0x418 > [] full_proxy_read+0xdc/0x148 > [] vfs_read+0x104/0x340 > [] ksys_read+0xf8/0x1e0 > [] __arm64_sys_read+0x74/0xa8 > [] invoke_syscall.constprop.0+0xdc/0x1d8 > [] do_el0_svc+0xe4/0x298 > [] el0_svc+0x20/0x30 > [] el0t_64_sync_handler+0xb0/0xb8 > [] el0t_64_sync+0x178/0x17c Can you shrink this a bit? > Fixes: 84a2bdb1b458fc968d6d9e07dab388dc679bd747 ("mm: slub: move sysfs slab alloc/free interfaces to debugfs") We use 12, which is shorter. > Link: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/mm/slub.c?h=next-20210617&id=84a2bdb1b458fc968d6d9e07dab388dc679bd747 > Must be no blank lines in the tag block. > Signed-off-by: Faiyaz Mohammed ... > static void *slab_debugfs_next(struct seq_file *seq, void *v, loff_t *ppos) > { > - loff_t *spos = v; > struct loc_track *t = seq->private; > > + v = ppos; > if (*ppos < t->count) { > - *ppos = ++*spos; > - return spos; > + ++*ppos; > + return v; > } > - *ppos = ++*spos; > + ++*ppos; > return NULL; Can it be v = ppos; ++*ppos; if (*ppos <= t->count) return v; return NULL; ? (basically the question is, is the comparison equivalent in this case or not) > } -- With Best Regards, Andy Shevchenko