Hi, Alexander, thanks a lot for your quick reply. > Not really - the crucial part is ->d_count == -128, i.e. it's already past > __dentry_kill(). Thanks a lot for your information, we would check this. > Which tree is that? > If you have some patches applied on top of that... We use Ubuntu Linux Kernel "4.15.0-42.45~16.04.1" from launchpad directly without any modification, the mapping Linux Kernel should be "4.15.18" according to https://people.canonical.com/~kernel/info/kernel-version-map.html On Mon, Apr 26, 2021 at 12:50 AM Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote: > > On Sun, Apr 25, 2021 at 11:22:15PM +0800, haosdent wrote: > > Hi, Alexander Viro and dear Linux Filesystems maintainers, recently we > > encounter a NULL pointer dereference Oops in our production. > > > > We have attempted to analyze the core dump and compare it with source code > > in the past few weeks, currently still could not understand why > > `dentry->d_inode` become NULL while other fields look normal. > > Not really - the crucial part is ->d_count == -128, i.e. it's already past > __dentry_kill(). > > > [19521409.514784] RIP: 0010:__atime_needs_update+0x5/0x190 > > Which tree is that? __atime_needs_update() had been introduced in > 4.8 and disappeared in 4.18; anything of that age straight on mainline > would have a plenty of interesting problems. If you have some patches > applied on top of that... Depends on what those are, obviously. -- Best Regards, Haosdent Huang
