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bh=XBWQd8JpXqPiSUXlz560wSrv6GFOWoMdAs6vQXNYcJk=; b=gY/yj1+YiF2aa+sRuRNpr1sU88/MDUuFLdSuh0h8OFnwBYEu01hBchFnlVFN+gmOESOGek f5PDsQjJsmHQVHvcNK8k7DWFrIskBRiun8xHI/eVWNSQUVMSv9vq7hmW7UmbgHVpBUw79s py/u+A/JC1SkTRu0xn1hCwhyZwtbAig= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-278-cP9HqQaYMY-UMqezcG8onw-1; Wed, 01 Feb 2023 04:14:02 -0500 X-MC-Unique: cP9HqQaYMY-UMqezcG8onw-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 32D1B183B3C3; Wed, 1 Feb 2023 09:14:02 +0000 (UTC) Received: from MiWiFi-R3L-srv.redhat.com (ovpn-13-89.pek2.redhat.com [10.72.13.89]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5E5C1492B01; Wed, 1 Feb 2023 09:13:57 +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, lstoakes@gmail.com, willy@infradead.org, hch@infradead.org, error27@gmail.com, Baoquan He Subject: [PATCH v4 3/7] mm/vmalloc.c: allow vread() to read out vm_map_ram areas Date: Wed, 1 Feb 2023 17:13:35 +0800 Message-Id: <20230201091339.61761-4-bhe@redhat.com> In-Reply-To: <20230201091339.61761-1-bhe@redhat.com> References: <20230201091339.61761-1-bhe@redhat.com> MIME-Version: 1.0 Content-type: text/plain X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: DA71C180012 X-Rspam-User: X-Stat-Signature: hyxnqshxqfa3i8nncmf1zkfq3mmfpbf1 X-HE-Tag: 1675242846-667714 X-HE-Meta: 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 ZMnVnAGj F/UtHxwvZcmx3g4NydsvLUpSZLh11G+eHhYYpGXGDti0QncX1YKS5GJF1QSJcMR3c3HkuI2bNHR11lWesQWMcqGwxS8u4reJXCZ9DB4gOx0lOYdFWNyFz0S0cIifzLjvsJvjO/4RzQWstr+dpbJ229jJT7TbUOvT75FMzORjOzZz5YBLB5rlnmMCr2Z7FqxmA0O8iZq54lgTevy6hQ1DsKFTu4m78PZU2BOXb6qzFyDKHrPE= 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 have an associated vm_struct. Then in vread(), these areas are all skipped. Here, add a new function vmap_ram_vread() to read out vm_map_ram areas. The area created with vmap_ram_vread() interface directly can be handled like the other normal vmap areas with aligned_vread(). While areas which will be further subdivided and managed with vmap_block need carefully read out page-aligned small regions and zero fill holes. Signed-off-by: Baoquan He Reviewed-by: Lorenzo Stoakes --- mm/vmalloc.c | 87 +++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 80 insertions(+), 7 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index ab4825050b5c..5a3ea6cb7ec2 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -3544,6 +3544,67 @@ static int aligned_vread(char *buf, char *addr, unsigned long count) return copied; } +static void vmap_ram_vread(char *buf, char *addr, int count, unsigned long flags) +{ + char *start; + struct vmap_block *vb; + unsigned long offset; + unsigned int rs, re, n; + + /* + * If it's area created by vm_map_ram() interface directly, but + * not further subdividing and delegating management to vmap_block, + * handle it here. + */ + if (!(flags & VMAP_BLOCK)) { + aligned_vread(buf, addr, count); + return; + } + + /* + * Area is split into regions and tracked with vmap_block, read out + * each region and zero fill the hole between regions. + */ + vb = xa_load(&vmap_blocks, addr_to_vb_idx((unsigned long)addr)); + if (!vb) + goto finished; + + spin_lock(&vb->lock); + if (bitmap_empty(vb->used_map, VMAP_BBMAP_BITS)) { + spin_unlock(&vb->lock); + goto finished; + } + for_each_set_bitrange(rs, re, vb->used_map, VMAP_BBMAP_BITS) { + if (!count) + break; + start = vmap_block_vaddr(vb->va->va_start, rs); + while (addr < start) { + if (count == 0) + break; + *buf = '\0'; + buf++; + addr++; + count--; + } + /*it could start reading from the middle of used region*/ + offset = offset_in_page(addr); + n = ((re - rs + 1) << PAGE_SHIFT) - offset; + if (n > count) + n = count; + aligned_vread(buf, start+offset, n); + + buf += n; + addr += n; + count -= n; + } + spin_unlock(&vb->lock); + +finished: + /* zero-fill the left dirty or free regions */ + if (count) + memset(buf, 0, count); +} + /** * vread() - read vmalloc area in a safe way. * @buf: buffer for reading data @@ -3574,7 +3635,7 @@ 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, flags; addr = kasan_reset_tag(addr); @@ -3595,12 +3656,21 @@ long vread(char *buf, char *addr, unsigned long count) if (!count) break; - if (!va->vm) + vm = va->vm; + flags = va->flags & VMAP_FLAGS_MASK; + /* + * VMAP_BLOCK indicates a sub-type of vm_map_ram area, need + * be set together with VMAP_RAM. + */ + WARN_ON(flags == VMAP_BLOCK); + + if (!vm && !flags) 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) @@ -3610,10 +3680,13 @@ 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 (flags & VMAP_RAM) + vmap_ram_vread(buf, addr, n, flags); + else if (!(vm->flags & VM_IOREMAP)) aligned_vread(buf, addr, n); else /* IOREMAP area is treated as memory hole */ memset(buf, 0, n);