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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 67A0DC433FE for ; Thu, 17 Nov 2022 01:36:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234600AbiKQBgZ (ORCPT ); Wed, 16 Nov 2022 20:36:25 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39000 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234016AbiKQBgX (ORCPT ); Wed, 16 Nov 2022 20:36:23 -0500 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:3::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A15055D689 for ; Wed, 16 Nov 2022 17:36:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=KgdSixELcD01KTtZwC87lYpf/UiRXAzRRNHLwpM4pFw=; b=1UeQXkf8h/lUY9LATNVCf1tt/N 4h5tUCij8ckaTmOJBdPFWkOMSahkhpCPdlkO2xRxieM43ny6C/S8BTc7tJzmTrGnuzWTNZJxdYlgq 832s9S4FRcgmKtUnDc0Zl3QaThsEQSmoUZB6mwoEEjTHIiv3Q5AJUG9RIT4t6hAga/n8MT60+KoMD zZilFVI+ZF101fP9wuXz0V2FsiVWd/D5BjrSHVEka7zKL1fkyoHMloZAnhq3s9vDRUh7KXlSeRr8/ Gi60LRmD9NldV+Al+InyslkGjn0NW7SM163BoMI5ekQ45Cs9PyyiVlmV/dCRB9OOIPG+7B0Z5jrgI De7/+bYQ==; Received: from mcgrof by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1ovTpA-009L1x-VG; Thu, 17 Nov 2022 01:36:16 +0000 Date: Wed, 16 Nov 2022 17:36:16 -0800 From: Luis Chamberlain To: Song Liu Cc: bpf@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, x86@kernel.org, peterz@infradead.org, hch@lst.de, rick.p.edgecombe@intel.com, aaron.lu@intel.com, rppt@kernel.org Subject: Re: [PATCH bpf-next v3 1/6] vmalloc: introduce execmem_alloc, execmem_free, and execmem_fill Message-ID: References: <20221117010621.1891711-1-song@kernel.org> <20221117010621.1891711-2-song@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221117010621.1891711-2-song@kernel.org> Sender: Luis Chamberlain Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Wed, Nov 16, 2022 at 05:06:16PM -0800, Song Liu wrote: > +static void move_vmap_to_free_text_tree(void *addr) > +{ > + struct vmap_area *va; > + > + /* remove from vmap_area_root */ > + spin_lock(&vmap_area_lock); > + va = __find_vmap_area((unsigned long)addr, &vmap_area_root); > + if (WARN_ON_ONCE(!va)) { > + spin_unlock(&vmap_area_lock); > + return; > + } > + unlink_va(va, &vmap_area_root); > + spin_unlock(&vmap_area_lock); > + > + /* make the memory RO+X */ > + memset(addr, 0, va->va_end - va->va_start); > + set_memory_ro(va->va_start, (va->va_end - va->va_start) >> PAGE_SHIFT); > + set_memory_x(va->va_start, (va->va_end - va->va_start) >> PAGE_SHIFT); > + > + /* add to all_text_vm */ > + va->vm->next = all_text_vm; > + all_text_vm = va->vm; > + > + /* add to free_text_area_root */ > + spin_lock(&free_text_area_lock); > + merge_or_add_vmap_area_augment(va, &free_text_area_root, &free_text_area_list); > + spin_unlock(&free_text_area_lock); > +} <-- snip --> > +void *execmem_alloc(unsigned long size, unsigned long align) > +{ > + struct vmap_area *va, *tmp; > + unsigned long addr; > + enum fit_type type; > + int ret; > + > + va = kmem_cache_alloc_node(vmap_area_cachep, GFP_KERNEL, NUMA_NO_NODE); > + if (unlikely(!va)) > + return NULL; > + > +again: > + preload_this_cpu_lock(&free_text_area_lock, GFP_KERNEL, NUMA_NO_NODE); > + tmp = find_vmap_lowest_match(&free_text_area_root, size, align, 1, false); > + > + if (!tmp) { > + unsigned long alloc_size; > + void *ptr; > + > + spin_unlock(&free_text_area_lock); > + > + /* > + * Not enough continuous space in free_text_area_root, try > + * allocate more memory. The memory is first added to > + * vmap_area_root, and then moved to free_text_area_root. > + */ > + alloc_size = roundup(size, PMD_SIZE * num_online_nodes()); > + ptr = __vmalloc_node_range(alloc_size, PMD_SIZE, EXEC_MEM_START, > + EXEC_MEM_END, GFP_KERNEL, PAGE_KERNEL, > + VM_ALLOW_HUGE_VMAP | VM_NO_GUARD, > + NUMA_NO_NODE, __builtin_return_address(0)); > + if (unlikely(!ptr)) > + goto err_out; > + > + move_vmap_to_free_text_tree(ptr); It's not perfectly clear to me how we know for sure nothing can take this underneath our noses. Luis