Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758514AbYG1QZ3 (ORCPT ); Mon, 28 Jul 2008 12:25:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754887AbYG1QZU (ORCPT ); Mon, 28 Jul 2008 12:25:20 -0400 Received: from e35.co.us.ibm.com ([32.97.110.153]:45434 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752053AbYG1QZS (ORCPT ); Mon, 28 Jul 2008 12:25:18 -0400 Date: Mon, 28 Jul 2008 11:25:03 -0500 From: Michael Halcrow To: Eric Sandeen Cc: linux-kernel Mailing List , Andrew Morton Subject: Re: [PATCH] eCryptfs - use page_alloc not kmalloc to get a page of memory Message-ID: <20080728162503.GC7234@halcrowt61p.austin.ibm.com> Reply-To: Michael Halcrow References: <488DF00F.3080809@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <488DF00F.3080809@redhat.com> User-Agent: Mutt/1.5.16 (2007-06-09) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3642 Lines: 114 On Mon, Jul 28, 2008 at 11:13:03AM -0500, Eric Sandeen wrote: > With SLUB debugging turned on in 2.6.26, I was getting memory corruption > when testing eCryptfs. The root cause turned out to be that eCryptfs > was doing kmalloc(PAGE_CACHE_SIZE); virt_to_page() and treating that > as a nice page-aligned chunk of memory. But at least with SLUB debugging > on, this is not always true, and the page we get from virt_to_page does > not necessarily match the PAGE_CACHE_SIZE worth of memory we got from > kmalloc. > > My simple testcase was 2 loops doing "rm -f fileX; cp /tmp/fileX ." for > 2 different multi-megabyte files. With this change I no longer see > the corruption. > > Thanks, > -Eric > > Signed-off-by: Eric Sandeen Acked-by: Michael Halcrow > --- > > Index: linux-2.6.26/fs/ecryptfs/crypto.c > =================================================================== > --- linux-2.6.26.orig/fs/ecryptfs/crypto.c > +++ linux-2.6.26/fs/ecryptfs/crypto.c > @@ -474,8 +474,8 @@ int ecryptfs_encrypt_page(struct page *p > { > struct inode *ecryptfs_inode; > struct ecryptfs_crypt_stat *crypt_stat; > - char *enc_extent_virt = NULL; > - struct page *enc_extent_page; > + char *enc_extent_virt; > + struct page *enc_extent_page = NULL; > loff_t extent_offset; > int rc = 0; > > @@ -491,14 +491,14 @@ int ecryptfs_encrypt_page(struct page *p > page->index); > goto out; > } > - enc_extent_virt = kmalloc(PAGE_CACHE_SIZE, GFP_USER); > - if (!enc_extent_virt) { > + enc_extent_page = alloc_page(GFP_USER); > + if (!enc_extent_page) { > rc = -ENOMEM; > ecryptfs_printk(KERN_ERR, "Error allocating memory for " > "encrypted extent\n"); > goto out; > } > - enc_extent_page = virt_to_page(enc_extent_virt); > + enc_extent_virt = kmap(enc_extent_page); > for (extent_offset = 0; > extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size); > extent_offset++) { > @@ -526,7 +526,10 @@ int ecryptfs_encrypt_page(struct page *p > } > } > out: > - kfree(enc_extent_virt); > + if (enc_extent_page) { > + kunmap(enc_extent_page); > + __free_page(enc_extent_page); > + } > return rc; > } > > @@ -608,8 +611,8 @@ int ecryptfs_decrypt_page(struct page *p > { > struct inode *ecryptfs_inode; > struct ecryptfs_crypt_stat *crypt_stat; > - char *enc_extent_virt = NULL; > - struct page *enc_extent_page; > + char *enc_extent_virt; > + struct page *enc_extent_page = NULL; > unsigned long extent_offset; > int rc = 0; > > @@ -626,14 +629,14 @@ int ecryptfs_decrypt_page(struct page *p > page->index); > goto out; > } > - enc_extent_virt = kmalloc(PAGE_CACHE_SIZE, GFP_USER); > - if (!enc_extent_virt) { > + enc_extent_page = alloc_page(GFP_USER); > + if (!enc_extent_page) { > rc = -ENOMEM; > ecryptfs_printk(KERN_ERR, "Error allocating memory for " > "encrypted extent\n"); > goto out; > } > - enc_extent_page = virt_to_page(enc_extent_virt); > + enc_extent_virt = kmap(enc_extent_page); > for (extent_offset = 0; > extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size); > extent_offset++) { > @@ -661,7 +664,10 @@ int ecryptfs_decrypt_page(struct page *p > } > } > out: > - kfree(enc_extent_virt); > + if (enc_extent_page) { > + kunmap(enc_extent_page); > + __free_page(enc_extent_page); > + } > return rc; > } > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/