From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 716EACD13CF for ; Mon, 2 Sep 2024 08:57:05 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 01B698D00A9; Mon, 2 Sep 2024 04:57:05 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EE4348D0065; Mon, 2 Sep 2024 04:57:04 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CC2168D00A9; Mon, 2 Sep 2024 04:57:04 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id AC9788D0065 for ; Mon, 2 Sep 2024 04:57:04 -0400 (EDT) Received: from smtpin28.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 3D7FC81A70 for ; Mon, 2 Sep 2024 08:57:04 +0000 (UTC) X-FDA: 82519193568.28.AE4ECF5 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.223.131]) by imf01.hostedemail.com (Postfix) with ESMTP id BA55F40011 for ; Mon, 2 Sep 2024 08:57:00 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=IaU8guUU; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=XxZIUg8E; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=IaU8guUU; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=XxZIUg8E; spf=pass (imf01.hostedemail.com: domain of vbabka@suse.cz designates 195.135.223.131 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1725267297; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=WSA9U7lugzB3ukAjYh0xJQNLZfRIb4q7TpGenVYMhdM=; b=rbwyDXWbZY2++Mkd/fLt8mQ+2+yXuPlmCnrhz5oCwR2ISIYy9LCJiTvj/s3n3oo05ihRfF bXuuDumOTeVmkGZrYqJICeH563cfpDjRORN3GE/UHiGIMRdLogbQ4d8X3uqxLw5d6Bkqx/ xbcAI9woA4AvLpBYG4eesQH8ZejI1Lk= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=IaU8guUU; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=XxZIUg8E; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=IaU8guUU; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=XxZIUg8E; spf=pass (imf01.hostedemail.com: domain of vbabka@suse.cz designates 195.135.223.131 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1725267297; a=rsa-sha256; cv=none; b=PWfMju4uYZPv5x9PFcGsj4T4k8BnOjBgEMehzJqkoHV1jOeCNxhztpIt4d0TKi4MmylXIB 2L1Y/pN06zKXMAKsRO3xJW/KJknx5nwrS3NhzRHzOScXldDcgE+C78ART4nbTuY9a6ZqS1 XxgNOv/1zMprhFYh8ad3dD7KITSPPzo= Received: from imap1.dmz-prg2.suse.org (imap1.dmz-prg2.suse.org [IPv6:2a07:de40:b281:104:10:150:64:97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id C0E8C1FB9D; Mon, 2 Sep 2024 08:56:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1725267418; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=WSA9U7lugzB3ukAjYh0xJQNLZfRIb4q7TpGenVYMhdM=; b=IaU8guUUCTm4JDib5mgg1mUuMLZh7uxJ7ZBnBsORedmn4RB9twHAuPDLb3FUAZBqArXSdJ 8ijReHu5Ux6xXtUTfab/8s50fn1aPCxf5mBantxLNe5KuSHlKWNMNITu2EVoBI5HwYTX4Q aVRYt7rIvrPpMGn1xrwosIdN4Rokvzs= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1725267418; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=WSA9U7lugzB3ukAjYh0xJQNLZfRIb4q7TpGenVYMhdM=; b=XxZIUg8EKw65nsI+ZTfV/pL4fvX10NqWFPcsq/znNaF29ywIK+ArgxR+XqqZoFEYjLMEx4 Rb9EPIxIpmiETGCg== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1725267418; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=WSA9U7lugzB3ukAjYh0xJQNLZfRIb4q7TpGenVYMhdM=; b=IaU8guUUCTm4JDib5mgg1mUuMLZh7uxJ7ZBnBsORedmn4RB9twHAuPDLb3FUAZBqArXSdJ 8ijReHu5Ux6xXtUTfab/8s50fn1aPCxf5mBantxLNe5KuSHlKWNMNITu2EVoBI5HwYTX4Q aVRYt7rIvrPpMGn1xrwosIdN4Rokvzs= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1725267418; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=WSA9U7lugzB3ukAjYh0xJQNLZfRIb4q7TpGenVYMhdM=; b=XxZIUg8EKw65nsI+ZTfV/pL4fvX10NqWFPcsq/znNaF29ywIK+ArgxR+XqqZoFEYjLMEx4 Rb9EPIxIpmiETGCg== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id 7F02913A7C; Mon, 2 Sep 2024 08:56:58 +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 3J9bHtp91WZhSgAAD6G6ig (envelope-from ); Mon, 02 Sep 2024 08:56:58 +0000 Message-ID: Date: Mon, 2 Sep 2024 10:56:57 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/2] mm: vmalloc: implement vrealloc() To: Feng Tang Cc: Danilo Krummrich , "cl@linux.com" , "penberg@kernel.org" , "rientjes@google.com" , "iamjoonsoo.kim@lge.com" , "akpm@linux-foundation.org" , "roman.gushchin@linux.dev" , "42.hyeyoo@gmail.com" <42.hyeyoo@gmail.com>, "urezki@gmail.com" , "hch@infradead.org" , "kees@kernel.org" , "ojeda@kernel.org" , "wedsonaf@gmail.com" , "mhocko@kernel.org" , "mpe@ellerman.id.au" , "chandan.babu@oracle.com" , "christian.koenig@amd.com" , "maz@kernel.org" , "oliver.upton@linux.dev" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "rust-for-linux@vger.kernel.org" , kasan-dev References: <20240722163111.4766-1-dakr@kernel.org> <20240722163111.4766-2-dakr@kernel.org> <07491799-9753-4fc9-b642-6d7d7d9575aa@suse.cz> <44fa564b-9c8f-4ac2-bce3-f6d2c99b73b7@suse.cz> Content-Language: en-US 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-Rspamd-Action: no action X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: BA55F40011 X-Stat-Signature: h5qs91jjstpeidif771ub6yfgyyeftoz X-Rspam-User: X-HE-Tag: 1725267420-938238 X-HE-Meta: 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 BIBZIqCg zObl3pkKkwIAxaEyl7mnFN6XRZOmzbVVpLo+pvR0aUd8W2jgnqMh9W/BcLZnOFayLDYZMTlhUwKyMEAqADua/y4hpeuqX3HCq5xNsKGuL6Mmgvqh60mWxZTgDNQn+cNarpWciCkjyM9piqgE1fdXVQ8A2KpjPvwV2UQ8jC/1zKJrWravW/SiuJVmX4I1frfpLmR/C+gHKd+A+i/GlxD4Oyo9G2Z33jgbJMXuPWGXnoLlIwSpgELx67aUCAEa63dZKsJ1XClMKbLSrOD6jAdiWzAJ10S/NS7Jk3ibw+xO6Mz+SNYhJL+qIYcezph+BMAblS3PztGFdNWuSo8KT5dOq91G1dFh2I64Y6BVi+HlPV38r0GRgdy83N4A8rQ5qKLxb1q8L0pjC8k7ELnb0X2snj4SqvA== 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 9/2/24 09:04, Feng Tang wrote: > On Mon, Sep 02, 2024 at 09:36:26AM +0800, Tang, Feng wrote: >> On Tue, Jul 30, 2024 at 08:15:34PM +0800, Vlastimil Babka wrote: >> > On 7/30/24 3:35 AM, Danilo Krummrich wrote: > [...] >> > >> > Let's say we kmalloc(56, __GFP_ZERO), we get an object from kmalloc-64 >> > cache. Since commit 946fa0dbf2d89 ("mm/slub: extend redzone check to >> > extra allocated kmalloc space than requested") and preceding commits, if >> > slub_debug is enabled (red zoning or user tracking), only the 56 bytes >> > will be zeroed. The rest will be either unknown garbage, or redzone. >> >> Yes. >> >> > >> > Then we might e.g. krealloc(120) and get a kmalloc-128 object and 64 >> > bytes (result of ksize()) will be copied, including the garbage/redzone. >> > I think it's fixable because when we do this in slub_debug, we also >> > store the original size in the metadata, so we could read it back and >> > adjust how many bytes are copied. >> >> krealloc() --> __do_krealloc() --> ksize() >> When ksize() is called, as we don't know what user will do with the >> extra space ([57, 64] here), the orig_size check will be unset by >> __ksize() calling skip_orig_size_check(). >> >> And if the newsize is bigger than the old 'ksize', the 'orig_size' >> will be correctly set for the newly allocated kmalloc object. Yes, but the memcpy() to the new object will be done using ksize() thus include the redzone, e.g. [57, 64] >> For the 'unstable' branch of -mm tree, which has all latest patches >> from Danilo, I run some basic test and it seems to be fine. To test it would not always be enough to expect some slub_debug to fail, you'd e.g. have to kmalloc(48, GFP_KERNEL | GFP_ZERO), krealloc(128, GFP_KERNEL | GFP_ZERO) and then verify there are zeroes from 48 to 128. I suspect there won't be zeroes from 48 to 64 due to redzone. (this would have made a great lib/slub_kunit.c test :)) > when doing more test, I found one case matching Vlastimil's previous > concern, that if we kzalloc a small object, and then krealloc with > a slightly bigger size which can still reuse the kmalloc object, > some redzone will be preserved. > > With test code like: > > buf = kzalloc(36, GFP_KERNEL); > memset(buf, 0xff, 36); > > buf = krealloc(buf, 48, GFP_KERNEL | __GFP_ZERO); > > Data after kzalloc+memset : > > ffff88802189b040: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > ffff88802189b050: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > ffff88802189b060: ff ff ff ff cc cc cc cc cc cc cc cc cc cc cc cc > ffff88802189b070: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc > > Data after krealloc: > > ffff88802189b040: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > ffff88802189b050: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > ffff88802189b060: ff ff ff ff cc cc cc cc cc cc cc cc cc cc cc cc > ffff88802189b070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > If we really want to make [37, 48] to be zeroed too, we can lift the > get_orig_size() from slub.c to slab_common.c and use it as the start > of zeroing in krealloc(). Or maybe just move krealloc() to mm/slub.c so there are no unnecessary calls between the files. We should also set a new orig_size in cases we are shrinking or enlarging within same object (i.e. 48->40 or 48->64). In case of shrinking, we also might need to redzone the shrinked area (i.e. [40, 48]) or later checks will fail. But if the current object is from kfence, then probably not do any of this... sigh this gets complicated. And really we need kunit tests for all the scenarios :/ > Thanks, > Feng