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[209.85.220.65]) by mx.google.com with SMTPS id h29sor11023530pgb.21.2019.07.16.08.27.34 for (Google Transport Security); Tue, 16 Jul 2019 08:27:34 -0700 (PDT) Received-SPF: pass (google.com: domain of lpf.vector@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b="nUXSP/Uj"; spf=pass (google.com: domain of lpf.vector@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=lpf.vector@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=bgQ4RhrQ8SIWyyg74Fp++hfL4YmAINorli25JMx+HLI=; b=nUXSP/UjVBYnWfyc4jlTs17JCc4taGD4zuIrEeMGCF2WE+YIc+d9FCDUzwatPo11yk HqC2h0chM/jepzjVBnURfdXKh25VLjxtjN/1Tz5ItpxKTcc9RlV2PUirx3R4MZ9atRtb jyoXVRhJYBvPOEsGIB+nAUr7ZtpzCFFjGenYYTgHkBxW9uDiT3Dlx7b4aRQe0wp41XBY OuKAUTgog5do0B51QJf+rsa0Ov9x9yXWySU4JP0CceKvQ6e9ynLGij7c7rE5pru5YcFI pSbKRZWDZtwkjTvmMa0g1ddOEPzMaYf4yutzX5TuXocttkvGc1syuWblapRkwporyYFy 6FqA== X-Google-Smtp-Source: APXvYqxqz7gSTFnrIhbMahLYP5IFtDrisUyyl7qIFt4erygqkCZSe869LC+F7nOwyncv1f9NyEyjzg== X-Received: by 2002:a63:490a:: with SMTP id w10mr34021506pga.6.1563290854559; Tue, 16 Jul 2019 08:27:34 -0700 (PDT) Received: from localhost.localdomain.localdomain ([2408:823c:c11:bf0:b8c3:8577:bf2f:2]) by smtp.gmail.com with ESMTPSA id h9sm27453651pgk.10.2019.07.16.08.27.25 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Tue, 16 Jul 2019 08:27:34 -0700 (PDT) From: Pengfei Li To: akpm@linux-foundation.org, willy@infradead.org Cc: urezki@gmail.com, rpenyaev@suse.de, peterz@infradead.org, guro@fb.com, rick.p.edgecombe@intel.com, rppt@linux.ibm.com, aryabinin@virtuozzo.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Pengfei Li Subject: [PATCH v6 2/2] mm/vmalloc: modify struct vmap_area to reduce its size Date: Tue, 16 Jul 2019 23:26:56 +0800 Message-Id: <20190716152656.12255-3-lpf.vector@gmail.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190716152656.12255-1-lpf.vector@gmail.com> References: <20190716152656.12255-1-lpf.vector@gmail.com> MIME-Version: 1.0 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: X-Virus-Scanned: ClamAV using ClamSMTP Objective --------- The current implementation of struct vmap_area wasted space. After applying this commit, sizeof(struct vmap_area) has been reduced from 11 words to 8 words. Description ----------- 1) Pack "subtree_max_size", "vm" and "purge_list". This is no problem because A) "subtree_max_size" is only used when vmap_area is in "free" tree B) "vm" is only used when vmap_area is in "busy" tree C) "purge_list" is only used when vmap_area is in vmap_purge_list 2) Eliminate "flags". Since only one flag VM_VM_AREA is being used, and the same thing can be done by judging whether "vm" is NULL, then the "flags" can be eliminated. Signed-off-by: Pengfei Li Suggested-by: Uladzislau Rezki (Sony) Reviewed-by: Uladzislau Rezki (Sony) --- include/linux/vmalloc.h | 20 +++++++++++++------- mm/vmalloc.c | 24 ++++++++++-------------- 2 files changed, 23 insertions(+), 21 deletions(-) diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h index 9b21d0047710..a1334bd18ef1 100644 --- a/include/linux/vmalloc.h +++ b/include/linux/vmalloc.h @@ -51,15 +51,21 @@ struct vmap_area { unsigned long va_start; unsigned long va_end; - /* - * Largest available free size in subtree. - */ - unsigned long subtree_max_size; - unsigned long flags; struct rb_node rb_node; /* address sorted rbtree */ struct list_head list; /* address sorted list */ - struct llist_node purge_list; /* "lazy purge" list */ - struct vm_struct *vm; + + /* + * The following three variables can be packed, because + * a vmap_area object is always one of the three states: + * 1) in "free" tree (root is vmap_area_root) + * 2) in "busy" tree (root is free_vmap_area_root) + * 3) in purge list (head is vmap_purge_list) + */ + union { + unsigned long subtree_max_size; /* in "free" tree */ + struct vm_struct *vm; /* in "busy" tree */ + struct llist_node purge_list; /* in purge list */ + }; }; /* diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 71d8040a8a0b..2f7edc0466e7 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -329,7 +329,6 @@ EXPORT_SYMBOL(vmalloc_to_pfn); #define DEBUG_AUGMENT_PROPAGATE_CHECK 0 #define DEBUG_AUGMENT_LOWEST_MATCH_CHECK 0 -#define VM_VM_AREA 0x04 static DEFINE_SPINLOCK(vmap_area_lock); /* Export for kexec only */ @@ -1115,7 +1114,7 @@ static struct vmap_area *alloc_vmap_area(unsigned long size, va->va_start = addr; va->va_end = addr + size; - va->flags = 0; + va->vm = NULL; insert_vmap_area(va, &vmap_area_root, &vmap_area_list); spin_unlock(&vmap_area_lock); @@ -1922,7 +1921,6 @@ void __init vmalloc_init(void) if (WARN_ON_ONCE(!va)) continue; - va->flags = VM_VM_AREA; va->va_start = (unsigned long)tmp->addr; va->va_end = va->va_start + tmp->size; va->vm = tmp; @@ -2020,7 +2018,6 @@ static void setup_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va, vm->size = va->va_end - va->va_start; vm->caller = caller; va->vm = vm; - va->flags |= VM_VM_AREA; spin_unlock(&vmap_area_lock); } @@ -2125,10 +2122,10 @@ struct vm_struct *find_vm_area(const void *addr) struct vmap_area *va; va = find_vmap_area((unsigned long)addr); - if (va && va->flags & VM_VM_AREA) - return va->vm; + if (!va) + return NULL; - return NULL; + return va->vm; } /** @@ -2149,11 +2146,10 @@ struct vm_struct *remove_vm_area(const void *addr) spin_lock(&vmap_area_lock); va = __find_vmap_area((unsigned long)addr); - if (va && va->flags & VM_VM_AREA) { + if (va && va->vm) { struct vm_struct *vm = va->vm; va->vm = NULL; - va->flags &= ~VM_VM_AREA; spin_unlock(&vmap_area_lock); kasan_free_shadow(vm); @@ -2856,7 +2852,7 @@ long vread(char *buf, char *addr, unsigned long count) if (!count) break; - if (!(va->flags & VM_VM_AREA)) + if (!va->vm) continue; vm = va->vm; @@ -2936,7 +2932,7 @@ long vwrite(char *buf, char *addr, unsigned long count) if (!count) break; - if (!(va->flags & VM_VM_AREA)) + if (!va->vm) continue; vm = va->vm; @@ -3466,10 +3462,10 @@ static int s_show(struct seq_file *m, void *p) va = list_entry(p, struct vmap_area, list); /* - * s_show can encounter race with remove_vm_area, !VM_VM_AREA on - * behalf of vmap area is being tear down or vm_map_ram allocation. + * s_show can encounter race with remove_vm_area, !vm on behalf + * of vmap area is being tear down or vm_map_ram allocation. */ - if (!(va->flags & VM_VM_AREA)) { + if (!va->vm) { seq_printf(m, "0x%pK-0x%pK %7ld vm_map_ram\n", (void *)va->va_start, (void *)va->va_end, va->va_end - va->va_start);