Hi,
I am facing an issue in v5.15 kernel due to " [PATCH v7 12/17] PCI:
Revoke mappings like devmem "related changes.
Whenever a PCI device (4f:00.0)is removed while being accessed from
user space (mmaped (sys/bus/pci/device/....4f:00.0/resource0)), no sig
bus error is raised. in earlier kernel v5.2, a sig bus error used to
get generated for this scenario.
In v5.15 5 kernel , value 0xffffffff is returned when the device is
plugged out or it is reset.
if the device is removed through "echo 1 >
/sys/bus/pci/devices/..4f:00.0/remove") command. user space code is
still able to access device memory no fault is generated in this case.
not sure if this is expected behavior. as the file which is mapped is
removed .(/sys/bus/pci/.../resource0)
After making the below change in v5.15 , I am able to get fault for
above scenarios. (device removal or unplug/reset.)
Please let me know if this is a new feature introduced to handle
mmaped memory access holes ? and allow to work inspite of sysfs files
removal.
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index d019d6ac6ad0..5f9b59ba8320 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -251,7 +251,7 @@ static const struct kernfs_ops sysfs_bin_kfops_mmap = {
.read = sysfs_kf_bin_read,
.write = sysfs_kf_bin_write,
.mmap = sysfs_kf_bin_mmap,
- .open = sysfs_kf_bin_open,
+// .open = sysfs_kf_bin_open,
};
Regards
Aravind
