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Thu, 10 Aug 2023 10:03:59 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 5nuMAA+21GRvEAAAMHmgww (envelope-from ); Thu, 10 Aug 2023 10:03:59 +0000 Message-ID: <37397d75-c95c-8730-cf22-79e283e0bd6c@suse.cz> Date: Thu, 10 Aug 2023 12:03:58 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.14.0 Subject: Re: [PATCH 2/2] mm/kmemleak: No need to check kmemleak_initialized in set_track_prepare() Content-Language: en-US To: Xiaolei Wang , catalin.marinas@arm.com, akpm@linux-foundation.org, glider@google.com, andreyknvl@gmail.com, zhaoyang.huang@unisoc.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20230810074704.2042664-1-xiaolei.wang@windriver.com> <20230810074704.2042664-3-xiaolei.wang@windriver.com> From: Vlastimil Babka In-Reply-To: <20230810074704.2042664-3-xiaolei.wang@windriver.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: B2E7F18000A X-Stat-Signature: af7t4gpuddj91e4jmcmrbcmijaunr1r7 X-Rspam-User: X-HE-Tag: 1691661840-774750 X-HE-Meta: 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 2WN1OU2S H2v9qqVlImP92ZV73xub/oe7eV9kknpXUw2xI6jObWDKcY2F+REBCaDm3s50dyQfJCGcOuI3BWP7s4B32DbmyUft+UIRE9rCFWt36Og31YQIl+x1NYoLbaZdC5LfbEI9MrazF4ghi4U6Ki81frDYn7p+pW+vA1eXI/uA4lwOaV1CItCTJDTjzewTdeVhB7uIFyNo+08StGUz0Ry7IQC0gxW+s2hiKgmpvfRnqoiOVk7RZXol37ZNWGoD9uRgkUoprcTsjWswC3Jjl1VDMbrncBtf1okgkzybTRudeHs5NhEdz9Z4= 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 8/10/23 09:47, Xiaolei Wang wrote: > The kmemleak_late_init() is defined as a late_initcall. The current > implementation of set_track_prepare() depends on the kmemleak init. > That also means there is no call trace for the memory leak which object > is created before the kmemleak_late_init(). So if I understand correctly, we have the following sequence of events durin boot ... A: stack_depot is initialized ... B: kmemleak is initialized ... before this patchset, we can miss allocations before B, aftewards only before A (which can't be helped), so we now have between A and B. That's nice, but it's weird that can record kmemleak when !kmemleak_initialized. Why can't it be initialized sooner in that case? > In a previous patch, we have fixed a bug in stack_depot_save() so that > it can be invoked even before stack depot is initialized. So there is > no reason to check the kmemleak_initialized in set_track_prepare(). > So delete the kmemleak_initialized judgment in set_track_prepare() > > unreferenced object 0xc674ca80 (size 64): > comm "swapper/0", pid 1, jiffies 4294938337 (age 204.880s) > hex dump (first 32 bytes): > 80 55 75 c6 80 54 75 c6 00 55 75 c6 80 52 75 c6 .Uu..Tu..Uu..Ru. > 00 53 75 c6 00 00 00 00 00 00 00 00 00 00 00 00 .Su.......... > > Fixes: 56a61617dd22 ("mm: use stack_depot for recording kmemleak's backtrace") > Signed-off-by: Xiaolei Wang > --- > mm/kmemleak.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/mm/kmemleak.c b/mm/kmemleak.c > index a2d34226e3c8..c9f2f816db19 100644 > --- a/mm/kmemleak.c > +++ b/mm/kmemleak.c > @@ -610,8 +610,6 @@ static noinline depot_stack_handle_t set_track_prepare(void) > unsigned long entries[MAX_TRACE]; > unsigned int nr_entries; > > - if (!kmemleak_initialized) > - return 0; > nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 3); > trace_handle = stack_depot_save(entries, nr_entries, GFP_NOWAIT); >