From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sergey Senozhatsky Subject: Re: [linux-next] mm/i915: i915_gemfs_init() NULL dereference Date: Thu, 1 Aug 2019 01:48:29 +0900 Message-ID: <20190731164829.GA399@tigerII.localdomain> References: <20190721142930.GA480@tigerII.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20190721142930.GA480@tigerII.localdomain> Sender: linux-kernel-owner@vger.kernel.org To: Sergey Senozhatsky Cc: Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , David Airlie , Daniel Vetter , Hugh Dickins , David Howells , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org List-Id: dri-devel@lists.freedesktop.org On (07/21/19 23:29), Sergey Senozhatsky wrote: > > BUG: kernel NULL pointer dereference, address: 0000000000000000 > #PF: supervisor instruction fetch in kernel mode > #PF: error_code(0x0010) - not-present page > PGD 0 P4D 0 > Oops: 0010 [#1] PREEMPT SMP PTI > RIP: 0010:0x0 > Code: Bad RIP value. > [..] > Call Trace: > i915_gemfs_init+0x6e/0xa0 [i915] > i915_gem_init_early+0x76/0x90 [i915] > i915_driver_probe+0x30a/0x1640 [i915] > ? kernfs_activate+0x5a/0x80 > ? kernfs_add_one+0xdd/0x130 > pci_device_probe+0x9e/0x110 > really_probe+0xce/0x230 > driver_probe_device+0x4b/0xc0 > device_driver_attach+0x4e/0x60 > __driver_attach+0x47/0xb0 > ? device_driver_attach+0x60/0x60 > bus_for_each_dev+0x61/0x90 > bus_add_driver+0x167/0x1b0 > driver_register+0x67/0xaa > ? 0xffffffffc0522000 > do_one_initcall+0x37/0x13f > ? kmem_cache_alloc+0x11a/0x150 > do_init_module+0x51/0x200 > __se_sys_init_module+0xef/0x100 > do_syscall_64+0x49/0x250 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 So "the new mount API" conversion probably looks like something below. But I'm not 100% sure. --- drivers/gpu/drm/i915/gem/i915_gemfs.c | 32 +++++++++++++++++++++------ 1 file changed, 25 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/i915/gem/i915_gemfs.c b/drivers/gpu/drm/i915/gem/i915_gemfs.c index 099f3397aada..2e365b26f8ee 100644 --- a/drivers/gpu/drm/i915/gem/i915_gemfs.c +++ b/drivers/gpu/drm/i915/gem/i915_gemfs.c @@ -7,12 +7,14 @@ #include #include #include +#include #include "i915_drv.h" #include "i915_gemfs.h" int i915_gemfs_init(struct drm_i915_private *i915) { + struct fs_context *fc; struct file_system_type *type; struct vfsmount *gemfs; @@ -36,19 +38,35 @@ int i915_gemfs_init(struct drm_i915_private *i915) struct super_block *sb = gemfs->mnt_sb; /* FIXME: Disabled until we get W/A for read BW issue. */ char options[] = "huge=never"; - int flags = 0; int err; - err = sb->s_op->remount_fs(sb, &flags, options); - if (err) { - kern_unmount(gemfs); - return err; - } + fc = fs_context_for_reconfigure(sb->s_root, 0, 0); + if (IS_ERR(fc)) + goto err; + + if (!fc->ops->parse_monolithic) + goto err; + + err = fc->ops->parse_monolithic(fc, options); + if (err) + goto err; + + if (!fc->ops->reconfigure) + goto err; + + err = fc->ops->reconfigure(fc); + if (err) + goto err; } i915->mm.gemfs = gemfs; - return 0; + +err: + pr_err("i915 gemfs init() failed\n"); + put_fs_context(fc); + kern_unmount(gemfs); + return -EINVAL; } void i915_gemfs_fini(struct drm_i915_private *i915) -- 2.22.0