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Tue, 08 Nov 2022 22:35:55 -0500 X-MC-Unique: p_3NSPWfPiGGUfTsv4bsoQ-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 616DD811E67; Wed, 9 Nov 2022 03:35:55 +0000 (UTC) Received: from MiWiFi-R3L-srv.redhat.com (ovpn-12-86.pek2.redhat.com [10.72.12.86]) by smtp.corp.redhat.com (Postfix) with ESMTP id A9D6C7AE5; Wed, 9 Nov 2022 03:35:51 +0000 (UTC) From: Baoquan He To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, akpm@linux-foundation.org, stephen.s.brennan@oracle.com, urezki@gmail.com, hch@infradead.org, Baoquan He Subject: [PATCH RFC 3/3] mm/vmalloc.c: allow vread() to read out vm_map_ram areas Date: Wed, 9 Nov 2022 11:35:34 +0800 Message-Id: <20221109033535.269229-4-bhe@redhat.com> In-Reply-To: <20221109033535.269229-1-bhe@redhat.com> References: <20221109033535.269229-1-bhe@redhat.com> MIME-Version: 1.0 Content-type: text/plain X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 ARC-Seal: i=1; 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dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=QtMqU1jz; spf=pass (imf03.hostedemail.com: domain of bhe@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=bhe@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-Rspamd-Server: rspam12 X-Rspam-User: X-Stat-Signature: fbfbxoo4bjjbap8y9ifjtbyyqzbqg3zm X-Rspamd-Queue-Id: 8BE7520004 X-HE-Tag: 1667965000-180990 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: Currently, vread() can read out vmalloc areas which is associated with a vm_struct. While this doesn't work for areas created by vm_map_ram() interface because it doesn't allocate a vm_struct. Then in vread(), these areas will be skipped. Here, add a new function vb_vread() to read out areas managed by vmap_block specifically. Then recognize vm_map_ram areas via vmap->flags and handle them respectively. Stephen Brennan Signed-off-by: Baoquan He Link: https://lore.kernel.org/all/87ilk6gos2.fsf@oracle.com/T/#u --- mm/vmalloc.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 51 insertions(+), 6 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 41d82dc07e13..5a8d5659bfb0 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -3518,6 +3518,46 @@ static int aligned_vread(char *buf, char *addr, unsigned long count) return copied; } +static void vb_vread(char *buf, char *addr, int count) +{ + char *start; + struct vmap_block *vb; + unsigned long offset; + unsigned int rs, re, n; + + offset = ((unsigned long)addr & (VMAP_BLOCK_SIZE - 1)) >> PAGE_SHIFT; + vb = xa_load(&vmap_blocks, addr_to_vb_idx((unsigned long)addr)); + + spin_lock(&vb->lock); + if (bitmap_empty(vb->used_map, VMAP_BBMAP_BITS)) { + spin_unlock(&vb->lock); + memset(buf, 0, count); + return; + } + for_each_set_bitrange(rs, re, vb->used_map, VMAP_BBMAP_BITS) { + if (!count) + break; + start = vmap_block_vaddr(vb->va->va_start, rs); + if (addr < start) { + if (count == 0) + break; + *buf = '\0'; + buf++; + addr++; + count--; + } + n = (re - rs + 1) << PAGE_SHIFT; + if (n > count) + n = count; + aligned_vread(buf, start, n); + + buf += n; + addr += n; + count -= n; + } + spin_unlock(&vb->lock); +} + /** * vread() - read vmalloc area in a safe way. * @buf: buffer for reading data @@ -3548,7 +3588,7 @@ long vread(char *buf, char *addr, unsigned long count) struct vm_struct *vm; char *vaddr, *buf_start = buf; unsigned long buflen = count; - unsigned long n; + unsigned long n, size; addr = kasan_reset_tag(addr); @@ -3569,12 +3609,14 @@ long vread(char *buf, char *addr, unsigned long count) if (!count) break; - if (!va->vm) + if (!(va->flags & VMAP_RAM) && !va->vm) continue; vm = va->vm; - vaddr = (char *) vm->addr; - if (addr >= vaddr + get_vm_area_size(vm)) + vaddr = (char *) va->va_start; + size = vm ? get_vm_area_size(vm) : va_size(va); + + if (addr >= vaddr + size) continue; while (addr < vaddr) { if (count == 0) @@ -3584,10 +3626,13 @@ long vread(char *buf, char *addr, unsigned long count) addr++; count--; } - n = vaddr + get_vm_area_size(vm) - addr; + n = vaddr + size - addr; if (n > count) n = count; - if (!(vm->flags & VM_IOREMAP)) + + if ((va->flags & (VMAP_RAM|VMAP_BLOCK)) == (VMAP_RAM|VMAP_BLOCK)) + vb_vread(buf, addr, n); + else if ((va->flags & VMAP_RAM) || !(vm->flags & VM_IOREMAP)) aligned_vread(buf, addr, n); else /* IOREMAP area is treated as memory hole */ memset(buf, 0, n);