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Thu, 5 Jun 2025 13:56:13 +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 wcDLL/2hQWhJPAAAD6G6ig (envelope-from ); Thu, 05 Jun 2025 13:56:13 +0000 Message-ID: <69a4b093-1fbd-4178-906b-960a3d8bc529@suse.cz> Date: Thu, 5 Jun 2025 15:56:13 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/vmstat: Fix build with MEMCG=y and VM_EVENT_COUNTERS=n Content-Language: en-US To: "Kirill A. Shutemov" Cc: Andrew Morton , David Hildenbrand , lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, rppt@kernel.org, surenb@google.com, mhocko@suse.com, hannes@cmpxchg.org, shakeel.butt@linux.dev, muchun.song@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Randy Dunlap , Konstantin Khlebnikov References: <20250604095111.533783-1-kirill.shutemov@linux.intel.com> <6fffd2fe-0cee-405f-af78-b57b5e5d02e8@suse.cz> <20250604142043.bdfdf4f9a6a6cbb57946f1a5@linux-foundation.org> <03c2b01b-18f5-4015-a19b-79b8af656697@suse.cz> <7lakc6hxbimvkgakpocj3aa65sdhmskm5p6hlurbwzyps33gfb@2z2eoz253hs4> From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSBWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmN6PsLBlAQTAQoAPgIbAwULCQgHAwUVCgkICwUWAgMBAAIe AQIXgBYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJnyBr8BQka0IFQAAoJECJPp+fMgqZkqmMQ AIbGN95ptUMUvo6aAdhxaOCHXp1DfIBuIOK/zpx8ylY4pOwu3GRe4dQ8u4XS9gaZ96Gj4bC+ jwWcSmn+TjtKW3rH1dRKopvC07tSJIGGVyw7ieV/5cbFffA8NL0ILowzVg8w1ipnz1VTkWDr 2zcfslxJsJ6vhXw5/npcY0ldeC1E8f6UUoa4eyoskd70vO0wOAoGd02ZkJoox3F5ODM0kjHu Y97VLOa3GG66lh+ZEelVZEujHfKceCw9G3PMvEzyLFbXvSOigZQMdKzQ8D/OChwqig8wFBmV QCPS4yDdmZP3oeDHRjJ9jvMUKoYODiNKsl2F+xXwyRM2qoKRqFlhCn4usVd1+wmv9iLV8nPs 2Db1ZIa49fJet3Sk3PN4bV1rAPuWvtbuTBN39Q/6MgkLTYHb84HyFKw14Rqe5YorrBLbF3rl M51Dpf6Egu1yTJDHCTEwePWug4XI11FT8lK0LNnHNpbhTCYRjX73iWOnFraJNcURld1jL1nV r/LRD+/e2gNtSTPK0Qkon6HcOBZnxRoqtazTU6YQRmGlT0v+rukj/cn5sToYibWLn+RoV1CE Qj6tApOiHBkpEsCzHGu+iDQ1WT0Idtdynst738f/uCeCMkdRu4WMZjteQaqvARFwCy3P/jpK uvzMtves5HvZw33ZwOtMCgbpce00DaET4y/UzsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZ8gcVAUJFhTonwAKCRAiT6fnzIKmZLY8D/9uo3Ut9yi2YCuASWxr7QQZ lJCViArjymbxYB5NdOeC50/0gnhK4pgdHlE2MdwF6o34x7TPFGpjNFvycZqccSQPJ/gibwNA zx3q9vJT4Vw+YbiyS53iSBLXMweeVV1Jd9IjAoL+EqB0cbxoFXvnjkvP1foiiF5r73jCd4PR rD+GoX5BZ7AZmFYmuJYBm28STM2NA6LhT0X+2su16f/HtummENKcMwom0hNu3MBNPUOrujtW khQrWcJNAAsy4yMoJ2Lw51T/5X5Hc7jQ9da9fyqu+phqlVtn70qpPvgWy4HRhr25fCAEXZDp xG4RNmTm+pqorHOqhBkI7wA7P/nyPo7ZEc3L+ZkQ37u0nlOyrjbNUniPGxPxv1imVq8IyycG AN5FaFxtiELK22gvudghLJaDiRBhn8/AhXc642/Z/yIpizE2xG4KU4AXzb6C+o7LX/WmmsWP Ly6jamSg6tvrdo4/e87lUedEqCtrp2o1xpn5zongf6cQkaLZKQcBQnPmgHO5OG8+50u88D9I rywqgzTUhHFKKF6/9L/lYtrNcHU8Z6Y4Ju/MLUiNYkmtrGIMnkjKCiRqlRrZE/v5YFHbayRD dJKXobXTtCBYpLJM4ZYRpGZXne/FAtWNe4KbNJJqxMvrTOrnIatPj8NhBVI0RSJRsbilh6TE m6M14QORSWTLRg== In-Reply-To: <7lakc6hxbimvkgakpocj3aa65sdhmskm5p6hlurbwzyps33gfb@2z2eoz253hs4> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; ARC_NA(0.00)[]; RCPT_COUNT_TWELVE(0.00)[15]; MIME_TRACE(0.00)[0:+]; FUZZY_BLOCKED(0.00)[rspamd.com]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; RCVD_TLS_ALL(0.00)[]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[linux-foundation.org,redhat.com,oracle.com,kernel.org,google.com,suse.com,cmpxchg.org,linux.dev,kvack.org,vger.kernel.org,infradead.org,gmail.com]; RCVD_COUNT_TWO(0.00)[2]; RCVD_VIA_SMTP_AUTH(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[intel.com:email,suse.cz:email,suse.cz:mid,imap1.dmz-prg2.suse.org:helo] X-Spam-Level: X-Spam-Flag: NO X-Spam-Score: -4.30 On 6/5/25 13:53, Kirill A. Shutemov wrote: > On Thu, Jun 05, 2025 at 08:19:28AM +0200, Vlastimil Babka wrote: >> On 6/4/25 23:20, Andrew Morton wrote: >> > On Wed, 4 Jun 2025 11:56:42 +0200 Vlastimil Babka wrote: >> > >> >> > There is no need to backport this fix to stable trees. Without the >> >> > strict BUILD_BUG_ON(), the issue is not harmful. The elements in >> >> > question would only be read by the memcg code, not by /proc/vmstat. >> >> > >> >> > Signed-off-by: Kirill A. Shutemov >> >> > Reported-by: Randy Dunlap >> >> > Fixes: ebc5d83d0443 ("mm/memcontrol: use vmstat names for printing statistics") >> >> >> >> Well in that case I think we should put Fixes: to the BUILD_BUG_ON() change. >> >> And if it's not yet a stable sha1, squash that together with this? >> >> It doesn't seem ebc5d83d0443 alone needs this fix. >> > >> > I shuffled things around. >> > >> > I moved "mm: strictly check vmstat_text array size" from mm-hotfixes >> > and back into mm-new for the next cycle. >> > >> > I reworked "mm/vmstat: fix build with MEMCG=y and VM_EVENT_COUNTERS=n" >> > so it precedes "mm: strictly check vmstat_text array size". >> > >> > I reworked "mm/vmstat: utilize designated initializers for the >> > vmstat_text array" so it comes last. >> > >> > >> > So the applying order is now >> >> I checked and in general it looks good, except a nit below. >> >> > mm-hotfixes: >> > mm-fix-vmstat-after-removing-nr_bounce.patch >> > >> > mm-new: >> > mm-vmstat-fix-build-with-memcg=y-and-vm_event_counters=n.patch >> > mm-strictly-check-vmstat_text-array-size.patch >> >> The changelogs of these two don't reflect the new ordering though, maybe >> Kirill can provide updated ones? > > Maybe something like this, for the first patch? LGTM, thanks! > > mm/vmstat: Make MEMCG select VM_EVENT_COUNTERS > > The vmstat_text array contains labels for counters displayed in /proc/vmstat. > It is important to keep the labels in sync with the counters. > > There is a BUILD_BUG_ON() check in vmstat_start() that ensures the size of the > vmstat_text is not smaller than VM_EVENT_COUNTERS. This helps to catch cases > where a new counter is added but the label is not. However, it does not help if > a counter is removed but the label remains. > > It would be nice to make the BUILD_BUG_ON() check more strict to catch such > cases. However, when compiling with MEMCG enabled but VM_EVENT_COUNTERS > disabled, the vmstat_text array is larger than NR_VMSTAT_ITEMS. > > This issue arises because some elements of the vmstat_text array are present > when either MEMCG or VM_EVENT_COUNTERS is enabled, but NR_VMSTAT_ITEMS only > accounts for these elements if VM_EVENT_COUNTERS is enabled. > > Instead of adjusting the NR_VMSTAT_ITEMS definition to account for MEMCG, make > MEMCG select VM_EVENT_COUNTERS. VM_EVENT_COUNTERS is enabled in most > configurations anyway. >