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Tue, 28 Jan 2025 15:45:01 +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 PYZ8I337mGdkPgAAD6G6ig (envelope-from ); Tue, 28 Jan 2025 15:45:01 +0000 Message-ID: <09484ff8-1b0c-4101-a793-e869aa8a6eeb@suse.cz> Date: Tue, 28 Jan 2025 16:45:01 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/5] mm: further refactor commit_merge() Content-Language: en-US To: Lorenzo Stoakes , Andrew Morton Cc: "Liam R . Howlett" , Jann Horn , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <0bbb2efbdc2ac2af2f6d73679cbb0811544d0647.1737929364.git.lorenzo.stoakes@oracle.com> 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: <0bbb2efbdc2ac2af2f6d73679cbb0811544d0647.1737929364.git.lorenzo.stoakes@oracle.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Action: no action X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 9C0FC20004 X-Stat-Signature: g1nosrxscubm3awinioawfxse7kksw39 X-HE-Tag: 1738079103-590534 X-HE-Meta: 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 IC722M+6 8Pn/72ZobYhqc+AYTSzMPXV+oivnnjYLbbpu/sFau+6MvlT8XHUW9HBm5oQTZy/QXNhC5K0s2cTNGIYRztRSuBWVF4YQMzGpy4+wRRFqe00dkZ4M+z+pQwMum80zz3YNq+/fPXJw0SeqQRoQXosIX3e92ChYwPQiZO7vDDh/OPDT9P+pFWFzcB1Go/wbCKh2O779WCHmGKeXHMHKFqcBFbA64AIKmGOVsMBzpO5Mj1327zGG3o/fQki4OzXwVUWvZKmLGU0Qx+9vfapctJhW/L72mKVYmL6uuYEnO X-Bogosity: Ham, tests=bogofilter, spamicity=0.007306, 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 1/27/25 16:50, Lorenzo Stoakes wrote: > --- a/mm/vma.h > +++ b/mm/vma.h > @@ -67,6 +67,16 @@ enum vma_merge_flags { > * at the gap. > */ > VMG_FLAG_JUST_EXPAND = 1 << 0, > + /* > + * Internal flag used during the merge operation to indicate we will > + * remove vmg->middle. > + */ > + __VMG_FLAG_REMOVE_MIDDLE = 1 << 1, > + /* > + * Internal flag used during the merge operationr to indicate we will > + * remove vmg->next. > + */ > + __VMG_FLAG_REMOVE_NEXT = 1 << 2, > }; Hm this is actually kinda weird? It's an enum, but the values of it are defined as different bits. And then struct vma_merge_struct has a "enum vma_merge_flags merge_flags;" but we don't store to it a single "enum vma_merge_flags" value defined above, but a combination of those. Is that even legal to do in C? AFAIK the more common pattern is enum that has normal incremental values that are used for the shifts. But I don't think we need all of this at all here? Just have bitfields in struct vma_merge_struct? bool just_expand : 1; bool remove_middle : 1; ... > /* > diff --git a/tools/testing/vma/vma.c b/tools/testing/vma/vma.c > index 3c0572120e94..8cce67237d86 100644 > --- a/tools/testing/vma/vma.c > +++ b/tools/testing/vma/vma.c > @@ -154,6 +154,9 @@ static void vmg_set_range(struct vma_merge_struct *vmg, unsigned long start, > vmg->end = end; > vmg->pgoff = pgoff; > vmg->flags = flags; > + > + vmg->merge_flags = VMG_FLAG_DEFAULT; > + vmg->target = NULL; > } > > /*