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authorVaibhav Jain <vaibhav@linux.vnet.ibm.com>2017-03-14 08:17:00 +0530
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-03-17 10:25:59 +0900
commit966fa72a716ceafc69de901a31f7cc1f52b35f81 (patch)
tree52858f2f4072a50127b18031ae2ac2279d5b73a9 /fs/kernfs
parent4495c08e84729385774601b5146d51d9e5849f81 (diff)
downloadop-kernel-dev-966fa72a716ceafc69de901a31f7cc1f52b35f81.zip
op-kernel-dev-966fa72a716ceafc69de901a31f7cc1f52b35f81.tar.gz
kernfs: Check KERNFS_HAS_RELEASE before calling kernfs_release_file()
Recently started seeing a kernel oops when a module tries removing a memory mapped sysfs bin_attribute. On closer investigation the root cause seems to be kernfs_release_file() trying to call kernfs_op.release() callback that's NULL for such sysfs bin_attributes. The oops occurs when kernfs_release_file() is called from kernfs_drain_open_files() to cleanup any open handles with active memory mappings. The patch fixes this by checking for flag KERNFS_HAS_RELEASE before calling kernfs_release_file() in function kernfs_drain_open_files(). On ppc64-le arch with cxl module the oops back-trace is of the form below: [ 861.381126] Unable to handle kernel paging request for instruction fetch [ 861.381360] Faulting instruction address: 0x00000000 [ 861.381428] Oops: Kernel access of bad area, sig: 11 [#1] .... [ 861.382481] NIP: 0000000000000000 LR: c000000000362c60 CTR: 0000000000000000 .... Call Trace: [c000000f1680b750] [c000000000362c34] kernfs_drain_open_files+0x104/0x1d0 (unreliable) [c000000f1680b790] [c00000000035fa00] __kernfs_remove+0x260/0x2c0 [c000000f1680b820] [c000000000360da0] kernfs_remove_by_name_ns+0x60/0xe0 [c000000f1680b8b0] [c0000000003638f4] sysfs_remove_bin_file+0x24/0x40 [c000000f1680b8d0] [c00000000062a164] device_remove_bin_file+0x24/0x40 [c000000f1680b8f0] [d000000009b7b22c] cxl_sysfs_afu_remove+0x144/0x170 [cxl] [c000000f1680b940] [d000000009b7c7e4] cxl_remove+0x6c/0x1a0 [cxl] [c000000f1680b990] [c00000000052f694] pci_device_remove+0x64/0x110 [c000000f1680b9d0] [c0000000006321d4] device_release_driver_internal+0x1f4/0x2b0 [c000000f1680ba20] [c000000000525cb0] pci_stop_bus_device+0xa0/0xd0 [c000000f1680ba60] [c000000000525e80] pci_stop_and_remove_bus_device+0x20/0x40 [c000000f1680ba90] [c00000000004a6c4] pci_hp_remove_devices+0x84/0xc0 [c000000f1680bad0] [c00000000004a688] pci_hp_remove_devices+0x48/0xc0 [c000000f1680bb10] [c0000000009dfda4] eeh_reset_device+0xb0/0x290 [c000000f1680bbb0] [c000000000032b4c] eeh_handle_normal_event+0x47c/0x530 [c000000f1680bc60] [c000000000032e64] eeh_handle_event+0x174/0x350 [c000000f1680bd10] [c000000000033228] eeh_event_handler+0x1e8/0x1f0 [c000000f1680bdc0] [c0000000000d384c] kthread+0x14c/0x190 [c000000f1680be30] [c00000000000b5a0] ret_from_kernel_thread+0x5c/0xbc Fixes: f83f3c515654 ("kernfs: fix locking around kernfs_ops->release() callback") Signed-off-by: Vaibhav Jain <vaibhav@linux.vnet.ibm.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/kernfs')
-rw-r--r--fs/kernfs/file.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index 8e4dc7a..ac2dfe0 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -809,7 +809,8 @@ void kernfs_drain_open_files(struct kernfs_node *kn)
if (kn->flags & KERNFS_HAS_MMAP)
unmap_mapping_range(inode->i_mapping, 0, 0, 1);
- kernfs_release_file(kn, of);
+ if (kn->flags & KERNFS_HAS_RELEASE)
+ kernfs_release_file(kn, of);
}
mutex_unlock(&kernfs_open_file_mutex);
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