On Thu, Jan 28, 2021 at 1:24 PM Kalesh Singh <kaleshsingh@xxxxxxxxxx> wrote: > > Android captures per-process system memory state when certain low memory > events (e.g a foreground app kill) occur, to identify potential memory > hoggers. In order to measure how much memory a process actually consumes, > it is necessary to include the DMA buffer sizes for that process in the > memory accounting. Since the handle to DMA buffers are raw FDs, it is > important to be able to identify which processes have FD references to > a DMA buffer. > > Currently, DMA buffer FDs can be accounted using /proc/<pid>/fd/* and > /proc/<pid>/fdinfo -- both are only readable by the process owner, > as follows: > 1. Do a readlink on each FD. > 2. If the target path begins with "/dmabuf", then the FD is a dmabuf FD. > 3. stat the file to get the dmabuf inode number. > 4. Read/ proc/<pid>/fdinfo/<fd>, to get the DMA buffer size. > > Accessing other processes’ fdinfo requires root privileges. This limits > the use of the interface to debugging environments and is not suitable > for production builds. Granting root privileges even to a system process > increases the attack surface and is highly undesirable. > > This series proposes making the requirement to read fdinfo less strict > with PTRACE_MODE_READ. > Hi everyone, I will send v2 of this patch series. Please let me know if you have any other comments or feedback, that should be addressed in the new version. Thanks, Kalesh > Kalesh Singh (2): > procfs: Allow reading fdinfo with PTRACE_MODE_READ > dmabuf: Add dmabuf inode no to fdinfo > > drivers/dma-buf/dma-buf.c | 1 + > fs/proc/base.c | 4 ++-- > fs/proc/fd.c | 15 ++++++++++++++- > 3 files changed, 17 insertions(+), 3 deletions(-) > > -- > 2.30.0.365.g02bc693789-goog >
