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Fri, 25 Oct 2024 17:40:43 +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 WkE8LRvYG2e/GAAAD6G6ig (envelope-from ); Fri, 25 Oct 2024 17:40:43 +0000 Message-ID: <10b88eed-7646-499c-9c67-d30469ee2357@suse.cz> Date: Fri, 25 Oct 2024 19:40:43 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 5/5] mm: defer second attempt at merge on mmap() Content-Language: en-US To: Lorenzo Stoakes , Andrew Morton Cc: "Liam R . Howlett" , Jann Horn , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Linus Torvalds , Peter Xu References: 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-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: CAEF110000D X-Stat-Signature: k9k1wd1zam7dtdrf4irfa5fouhfk45ax X-HE-Tag: 1729878007-623549 X-HE-Meta: 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 f95welty vew4T3poF7crW89jwWge1Cq/a4fIMPPYkxppJhTDLVQPFXTSof3Ql78GaeMlF+v6/zBsMuU1KRpcJQLg8+b28cn5i8r1i97ErgBqVtho6CKpFB4B8JhDRSPWGZT0L90HjY8DxQYVf5E5cI8OM2wEoE9G66DEi2WJ+XHDjmYgLxuitMlpjQzPB5SJyMC3kJSycaLNKbLXCGMByGJgM+YsVfxdBuvjdTN5ICNzGTPRXuWfg+wN6OnVIchNMPF1clh6A3sOavQN7q7fofvvoJ856iGbGDuWkffHkgNYTC3+ACL11crv7+SNex6XOUg== 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 10/25/24 14:26, Lorenzo Stoakes wrote: > Rather than trying to merge again when ostensibly allocating a new VMA, > instead defer until the VMA is added and attempt to merge the existing > range. > > This way we have no complicated unwinding logic midway through the process > of mapping the VMA. > > In addition this removes limitations on the VMA not being able to be the > first in the virtual memory address space which was previously implicitly > required. > > In theory, for this very same reason, we should unconditionally attempt > merge here, however this is likely to have a performance impact so it is > better to avoid this given the unlikely outcome of a merge. > > Reviewed-by: Vlastimil Babka > Signed-off-by: Lorenzo Stoakes > --- > mm/vma.c | 55 ++++++++++++++----------------------------------------- > 1 file changed, 14 insertions(+), 41 deletions(-) > > diff --git a/mm/vma.c b/mm/vma.c > index 7c690be67910..7194f9449c60 100644 > --- a/mm/vma.c > +++ b/mm/vma.c > @@ -19,6 +19,7 @@ struct mmap_state { > struct file *file; > > unsigned long charged; > + bool retry_merge; > > struct vm_area_struct *prev; > struct vm_area_struct *next; > @@ -2278,8 +2279,9 @@ static int __mmap_prepare(struct mmap_state *map, struct list_head *uf) > return 0; > } > > + > static int __mmap_new_file_vma(struct mmap_state *map, > - struct vm_area_struct **vmap, bool *mergedp) > + struct vm_area_struct **vmap) AFAICS **vmap could become *vma now > { > struct vma_iterator *vmi = map->vmi; > struct vm_area_struct *vma = *vmap;