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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> ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1668648986; a=rsa-sha256; cv=none; b=7SyZk/FEMaM03dxlARvTJ1Y40WaxXZhcsyMsPNOQj4+1CzqjxlcqIj6E7SIMkSfjQKMZGT tedtWPbmRqBkVNmu/aMMfylDtQ+gppC3txFFKp0OgSiDz1W7wSWmkdv9VSZSVMCQHPqbl5 0NytdQLjH8sAUojX8BMEMjKVc5dAap0= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=1UeQXkf8; 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spf=none (imf25.hostedemail.com: domain of mcgrof@infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=mcgrof@infradead.org; dmarc=fail reason="No valid SPF, DKIM not aligned (relaxed)" header.from=kernel.org (policy=none) X-HE-Tag: 1668648986-76619 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: 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