On Wed, Feb 20, 2019 at 05:18:48PM +0800, Gao Xiang wrote:
commit 51232df5e4b268936beccde5248f312a316800be upstream.
When the managed cache is enabled, the last reference count of a workgroup must be used for its workstation.
Otherwise, it could lead to incorrect (un)freezes in the reclaim path, and it would be harmful.
A typical race as follows:
Thread 1 (In the reclaim path) Thread 2 workgroup_freeze(grp, 1) refcnt = 1 ... workgroup_unfreeze(grp, 1) refcnt = 1 workgroup_get(grp) refcnt = 2 (x) workgroup_put(grp) refcnt = 1 (x) ...unexpected behaviors
- grp is detached but still used, which violates cache-managed freeze constraint.
Reviewed-by: Chao Yu yuchao0@huawei.com Signed-off-by: Gao Xiang gaoxiang25@huawei.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Gao Xiang gaoxiang25@huawei.com
Conflicts: drivers/staging/erofs/utils.c Updates: include/linux/xarray.h: add xa_untag_pointer,xa_tag_pointer,xa_pointer_tag from upstream 3159f943aafd in order to reduce conflicts.
No, sorry, I don't want to add xarray.h to 4.19.y, that's crazy.
And even if we did, you do not slip it in as part of a different patch, it should come in as its own patch, with the same git commit id that it landed in 4.20 with.
Please fix this up...
greg k-h