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[209.85.220.65]) by mx.google.com with SMTPS id bc5sor25078703plb.36.2019.07.16.06.26.56 for (Google Transport Security); Tue, 16 Jul 2019 06:26:56 -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=R46pC3b7; 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=2FLMt1biejUADnaZS+D7n9SrnPK40F0jXQ5om7TEM0E=; b=R46pC3b7xctfYiDbpcjsza4HTmNx/760I2ZaF5EDledhg5vHet72yrOirw34e4/Hwj a9XoTMetn8gr04TAIhE2LlWxSqPKgOVdS86OM+fcojB7GI2ad77E+i1jpeqKV1+2cEXe 2cnBZvd8RrCgjlzvvKJMItIGEgUzHUMwqJ08iwCMu+urNd/gsaxKdt4ji6oD/yqJ9OIH iA7wIo+ojN1xpialB5aVNj6g/NfG5lUi4MGaFRthczcja3mE2vVQnE/lPC/wRJoliTKR cdRyNH5A1gPD9fXBd/AjwTF+98c6JPOq0uOF0Ht1KinYxfj2YU02TOo6Oqg1Dy5trgYY UGYg== X-Google-Smtp-Source: APXvYqwLdB8Cef6LQ3pqCCQ0P7hsVjjgWF54ZHRKloxBfozTuaD/IY5JZ7PR7zFLuVVRnsib5VBBgA== X-Received: by 2002:a17:902:7448:: with SMTP id e8mr35514887plt.85.1563283615828; Tue, 16 Jul 2019 06:26:55 -0700 (PDT) Received: from localhost.localdomain.localdomain ([2408:823c:c11:bf0:b8c3:8577:bf2f:2]) by smtp.gmail.com with ESMTPSA id q1sm21472311pfg.84.2019.07.16.06.26.48 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Tue, 16 Jul 2019 06:26:55 -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 v5 2/2] mm/vmalloc: modify struct vmap_area to reduce its size Date: Tue, 16 Jul 2019 21:26:04 +0800 Message-Id: <20190716132604.28289-3-lpf.vector@gmail.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190716132604.28289-1-lpf.vector@gmail.com> References: <20190716132604.28289-1-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) --- 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..39bf9cf4175a 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. + * If !va->vm then this vmap_area object is allocated + * by vm_map_ram. */ - 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);