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Fri, 15 Mar 2024 13:07:45 +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 bd4ZHCFI9GXQIwAAD6G6ig (envelope-from ); Fri, 15 Mar 2024 13:07:45 +0000 Message-ID: <3bd30334-0a46-4050-930f-7f606a72b3e7@suse.cz> Date: Fri, 15 Mar 2024 14:07:45 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm,page_owner: Fix recursion Content-Language: en-US To: Oscar Salvador , Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Michal Hocko , Marco Elver , Andrey Konovalov , Alexander Potapenko References: <20240313234245.18824-1-osalvador@suse.de> From: Vlastimil Babka In-Reply-To: <20240313234245.18824-1-osalvador@suse.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 7A1D0120011 X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: dnd8kctyxaqfk55jyj7a8iidig6tdj8u X-HE-Tag: 1710508067-486919 X-HE-Meta: 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 96iVXgHJ mzTf4mtzgAROcDQ6z8UO7Ay4tjlp0tD7kGWKOyQWJ9qef063+GqudjaIx0wGOmrW1jYS7jRxsJAEjYHFJRQ7SSWatTOj5ZnWNlaGuhYMdwlgdw0j7mA2kxz4XxMhlDEBfWghlk0HPAkvDp1RCHiDUYMnIz8SelYTHMXvlQklrxz4gnhNzAbQjv3qVD9YCjbrLYdWamFMPXSQbpX9hcLiDLYWct/XDXoT3xpyRYARTfilX62xYje41FE4flxeBYCObn7mcmCVC7QXO0L2u5cjG41AeLILlWST1jFtFTw4K6YFVT4SDR6QGQokHTA== 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 3/14/24 00:42, Oscar Salvador wrote: > Prior to 217b2119b9e2 ("mm,page_owner: implement the tracking of the stacks count") > the only place where page_owner could potentially go into recursion due to > its need of allocating more memory was in save_stack(), which ends up calling > into stackdepot code with the possibility of allocating memory. > > We made sure to guard against that by signaling that the current task was > already in page_owner code, so in case a recursion attempt was made, we > could catch that and return dummy_handle. > > After above commit, a new place in page_owner code was introduced where we > could allocate memory, meaning we could go into recursion would we take that > path. > > Make sure to signal that we are in page_owner in that codepath as well. > Move the guard code into two helpers {un}set_current_in_page_owner() > and use them prior to calling in the two functions that might allocate > memory. > > Signed-off-by: Oscar Salvador > Fixes: 217b2119b9e2 ("mm,page_owner: implement the tracking of the stacks count") > --- > mm/page_owner.c | 30 +++++++++++++++++++++--------- > 1 file changed, 21 insertions(+), 9 deletions(-) > > @@ -292,7 +302,9 @@ noinline void __set_page_owner(struct page *page, unsigned short order, > return; > __set_page_owner_handle(page_ext, handle, order, gfp_mask); > page_ext_put(page_ext); > + set_current_in_page_owner(); > inc_stack_record_count(handle, gfp_mask); > + unset_current_in_page_owner(); This is because of the kmalloc() in add_stack_record_to_list() right? Why not wrap just that then? > } > > void __set_page_owner_migrate_reason(struct page *page, int reason)