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Fri, 28 Feb 2025 10:12:48 +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 a1zKNiCMwWcgXQAAD6G6ig (envelope-from ); Fri, 28 Feb 2025 10:12:48 +0000 Message-ID: <076a6867-20f5-4386-bc8e-2e7999b39431@suse.cz> Date: Fri, 28 Feb 2025 11:12:48 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/page_alloc: Add lockdep assertion for pageblock type change Content-Language: en-US To: Brendan Jackman , Andrew Morton Cc: David Hildenbrand , Oscar Salvador , Johannes Weiner , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20250227-pageblock-lockdep-v1-1-3701efb331bb@google.com> <20250227143302.2338b1cf15919c64a6c1eb27@linux-foundation.org> 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+fMgqZkBQJkBREIBQkRadznAAoJECJPp+fMgqZkNxIQ ALZRqwdUGzqL2aeSavbum/VF/+td+nZfuH0xeWiO2w8mG0+nPd5j9ujYeHcUP1edE7uQrjOC Gs9sm8+W1xYnbClMJTsXiAV88D2btFUdU1mCXURAL9wWZ8Jsmz5ZH2V6AUszvNezsS/VIT87 AmTtj31TLDGwdxaZTSYLwAOOOtyqafOEq+gJB30RxTRE3h3G1zpO7OM9K6ysLdAlwAGYWgJJ V4JqGsQ/lyEtxxFpUCjb5Pztp7cQxhlkil0oBYHkudiG8j1U3DG8iC6rnB4yJaLphKx57NuQ PIY0Bccg+r9gIQ4XeSK2PQhdXdy3UWBr913ZQ9AI2usid3s5vabo4iBvpJNFLgUmxFnr73SJ KsRh/2OBsg1XXF/wRQGBO9vRuJUAbnaIVcmGOUogdBVS9Sun/Sy4GNA++KtFZK95U7J417/J Hub2xV6Ehc7UGW6fIvIQmzJ3zaTEfuriU1P8ayfddrAgZb25JnOW7L1zdYL8rXiezOyYZ8Fm ZyXjzWdO0RpxcUEp6GsJr11Bc4F3aae9OZtwtLL/jxc7y6pUugB00PodgnQ6CMcfR/HjXlae h2VS3zl9+tQWHu6s1R58t5BuMS2FNA58wU/IazImc/ZQA+slDBfhRDGYlExjg19UXWe/gMcl De3P1kxYPgZdGE2eZpRLIbt+rYnqQKy8UxlszsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZAUSmwUJDK5EZgAKCRAiT6fnzIKmZOJGEACOKABgo9wJXsbWhGWYO7mD 8R8mUyJHqbvaz+yTLnvRwfe/VwafFfDMx5GYVYzMY9TWpA8psFTKTUIIQmx2scYsRBUwm5VI EurRWKqENcDRjyo+ol59j0FViYysjQQeobXBDDE31t5SBg++veI6tXfpco/UiKEsDswL1WAr tEAZaruo7254TyH+gydURl2wJuzo/aZ7Y7PpqaODbYv727Dvm5eX64HCyyAH0s6sOCyGF5/p eIhrOn24oBf67KtdAN3H9JoFNUVTYJc1VJU3R1JtVdgwEdr+NEciEfYl0O19VpLE/PZxP4wX PWnhf5WjdoNI1Xec+RcJ5p/pSel0jnvBX8L2cmniYnmI883NhtGZsEWj++wyKiS4NranDFlA HdDM3b4lUth1pTtABKQ1YuTvehj7EfoWD3bv9kuGZGPrAeFNiHPdOT7DaXKeHpW9homgtBxj 8aX/UkSvEGJKUEbFL9cVa5tzyialGkSiZJNkWgeHe+jEcfRT6pJZOJidSCdzvJpbdJmm+eED w9XOLH1IIWh7RURU7G1iOfEfmImFeC3cbbS73LQEFGe1urxvIH5K/7vX+FkNcr9ujwWuPE9b 1C2o4i/yZPLXIVy387EjA6GZMqvQUFuSTs/GeBcv0NjIQi8867H3uLjz+mQy63fAitsDwLmR EP+ylKVEKb0Q2A== In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: pbuxp3egkmd4puaqrs1bedur89scrs1z X-Rspamd-Queue-Id: 82C5E1A000D X-Rspamd-Server: rspam07 X-HE-Tag: 1740737570-908980 X-HE-Meta: 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 06SZ2Tah VwZXG3U4WhmwEqa0YR+LNso5Oo1ro9dMD+2nL+EDinlXRClWLlfLnptx+cEs0E6WCATWIQ5EQXQm6I34CdM4uAeexdJkqmPyUBN0z+U3yAlNTT/hUZSl93OW3WK7a3CdB+dAi+GhxYNhW8aSfPruTD+tsFqFECESXtxAwMBm3mPoRJeAN5/UxpO88mENRXoZXzTPFUpow50+o0XBMNyCMWT2aC4ha4F2z9RolngqTHYBzOD+75vUvzTmhKAsIIPw7UNJBE94T3eESRCL1z3myukGzyNBWRJPuP7j8UFLyviE5N3N93jdMmgzyCZu8MUlPP3ljYGB9rhJxSBuANZuG2xqMVTw76eFKajFhEa9eHhJc54l81dsEVZedFu6Sl7ueUeBnUhPI526AIxMl/IuiI/VCAA== 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 2/28/25 10:20, Brendan Jackman wrote: > On Thu, Feb 27, 2025 at 02:33:02PM -0800, Andrew Morton wrote: >> On Thu, 27 Feb 2025 16:15:47 +0000 Brendan Jackman wrote: >> >> > Since the migratetype hygiene patches [0], the locking here is >> > a bit more formalised, so write it down with an assert. >> > >> > ... >> > >> > --- a/mm/page_alloc.c >> > +++ b/mm/page_alloc.c >> > @@ -417,6 +417,10 @@ void set_pfnblock_flags_mask(struct page *page, unsigned long flags, >> > >> > void set_pageblock_migratetype(struct page *page, int migratetype) >> > { >> > + lockdep_assert_once(system_state == SYSTEM_BOOTING || >> > + in_mem_hotplug() || >> > + lockdep_is_held(&page_zone(page)->lock)); >> > + >> > if (unlikely(page_group_by_mobility_disabled && >> > migratetype < MIGRATE_PCPTYPES)) >> > migratetype = MIGRATE_UNMOVABLE; >> > >> >> We could add such assertions all over the place. Why this place in >> particular? > > For the other stuff, it's pretty obvious that it would be protected by > the zone lock (or, I don't know about it!). But it didn't seem totally > self-evident to me that it should protect the pageblock type. So it > seems particularly helpful to have it written in the code. I guess that's a good addition to the changelog. Acked-by: Vlastimil Babka > > I may be heavily biased about this though, because of the code I'm > working on for [0]. I use the pageblock type to remember whether it's > mapped in the ASI restricted address space. > > [0] https://lore.kernel.org/linux-mm/CA+i-1C1gOBLxRxE5YFGzeayYWBYyE_X6oH4D=9eVePt4=ehTig@mail.gmail.com/T/ >