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Tue, 13 Feb 2024 15:28:19 +0000 (UTC) Received: from dovecot-director2.suse.de ([10.150.64.162]) by imap2.dmz-prg2.suse.org with ESMTPSA id kxJfC5OKy2ULfAAAn2gu4w (envelope-from ); Tue, 13 Feb 2024 15:28:19 +0000 Date: Tue, 13 Feb 2024 16:29:28 +0100 From: Oscar Salvador To: Vlastimil Babka Cc: Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Michal Hocko , Marco Elver , Andrey Konovalov , Alexander Potapenko Subject: Re: [PATCH v8 2/5] mm,page_owner: Implement the tracking of the stacks count Message-ID: References: <20240212223029.30769-1-osalvador@suse.de> <20240212223029.30769-3-osalvador@suse.de> <8ff46f99-d167-448f-9aae-a634b8aae4d0@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8ff46f99-d167-448f-9aae-a634b8aae4d0@suse.cz> X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 6B7DE10000D X-Stat-Signature: unues8nniys7zboqrctjsy4414wduuaz X-Rspam-User: X-HE-Tag: 1707838101-651875 X-HE-Meta: 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 CltlT3qs l0fGipeLqe+ghyECCkt4wsvChgrFuxZIAvLMT8x6ZYs6s+ArGhdHcvoAgNIo4wWHZ/Rhqqrm7QhEs9DmfdFGqaPjHZ0Nf4Ca2QkhE3w73YXGXs4Mo171Kmb5D3RSAKI+yng9Itnufx/IruZfJLP5evT88lMckMnyvJOZcuPae3DITVt9oTfzlUPYczG6dRZVdwAMM0EyIU0KdVUCjqNzQRO87Z517EnQa/XSw 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 Tue, Feb 13, 2024 at 02:42:25PM +0100, Vlastimil Babka wrote: > On 2/12/24 23:30, Oscar Salvador wrote: > > __set_page_owner_handle(page_ext, handle, order, gfp_mask); > > page_ext_put(page_ext); > > + inc_stack_record_count(handle); > > What if this is dummy handle, which means we have recursed in page owner, > and we'll by trying to kmalloc() its struct stack and link it to the > stack_list because it was returned for the first time? Also failure_handle. > Could you pre-create static (not kmalloc) struct stack for these handles > with refcount of 0 and insert them to stack_list, all during > init_page_owner()? Bonus: no longer treating stack_list == NULL in a special > way in add_stack_record_to_list() (although you don't need to handle it > extra even now, AFAICS). Good catch. I did not think about this scenario, but this could definitely happen. Yeah, maybe creating an array of 2 structs for {dummy,failure}_handle and link them into stack_list. I thought about giving them a refcount of 1, because we only print stacks which refcount > 1 anyways, but setting it to 0 has comes with the advantage of catching spurious increments, should someone call refcount_inc on those (which should not really happen). I will try to implement it. Thanks -- Oscar Salvador SUSE Labs