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Howlett" , Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Lorenzo Stoakes , Jann Horn References: <20241031193608.1965366-1-Liam.Howlett@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: <20241031193608.1965366-1-Liam.Howlett@oracle.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Action: no action X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 191CB140021 X-Stat-Signature: xk5yenguwe6exdyd4r17cuaw7ursy896 X-Rspam-User: X-HE-Tag: 1730411057-185643 X-HE-Meta: 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 OFSP0IUQ SQUMAVf6q+SQfsVPb5GMSeVCAzc4BasLScZia1xPL9lAOi+b1Q0ee3WsK/kZ93fg8CKJKFFUvzsrD8spbV20pgXpN5nS34uy6apoLp2q9vkB+IwsAIjqnYDWvJ02EURv7TiW5uMD1P1P1MysRFFIq6HgQELLWq3z2wV7zLpjhONQTuceNDFCxV3ptE2g7aKx2Ot5kFfn34G78C9ycUrXcRTyvKPQ7vfRDdHindUwTT4/rVeriN/7nfMqwcE7lyZRTPPuP/E64j6PXmIxPdSlyYRxarEvFBm+dV7pSL/mjOgns2ichpOnyaG3dH0gI62k62FsH9KzXI7cV4/Q= 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 10/31/24 20:36, Liam R. Howlett wrote: > From: "Liam R. Howlett" > > There have been no reported infinite loops in the tree, but checking the > detection of an infinite loop during validation is simple enough. Add > the detection to the validate_mm() function so that error reports are > clear and don't just report stalls. > > This does not protect against internal maple tree issues, but it does > detect too many vmas being returned from the tree. > > The variance of +10 is to allow for the debugging output to be more useful for > nearly correct counts. In the event of more than 10 over the map_count, the > count will be set to -1 for easier identification of a potential infinite loop. > > Note that the mmap lock is held to ensure a consistent tree state during the > validation process. > > Signed-off-by: Liam R. Howlett > Cc: Lorenzo Stoakes > Cc: Vlastimil Babka > Cc: Jann Horn Reviewed-by: Vlastimil Babka > --- > mm/vma.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/mm/vma.c b/mm/vma.c > index 68138e8c153e..283e6bc4884f 100644 > --- a/mm/vma.c > +++ b/mm/vma.c > @@ -615,7 +615,10 @@ void validate_mm(struct mm_struct *mm) > anon_vma_unlock_read(anon_vma); > } > #endif > - i++; > + if (++i > mm->map_count + 10) { > + i = -1; > + break; > + } > } > if (i != mm->map_count) { > pr_emerg("map_count %d vma iterator %d\n", mm->map_count, i);