| Message ID | 20220623220613.3014268-1-kaleshsingh@google.com |
|---|---|
| Headers | show |
| Series | procfs: Add file path and size to /proc/<pid>/fdinfo | expand |
On Tue, Jun 28, 2022 at 4:54 AM Brian Foster <bfoster@redhat.com> wrote: > > On Thu, Jun 23, 2022 at 03:06:06PM -0700, Kalesh Singh wrote: > > To be able to account the amount of memory a process is keeping pinned > > by open file descriptors add a 'size' field to fdinfo output. > > > > dmabufs fds already expose a 'size' field for this reason, remove this > > and make it a common field for all fds. This allows tracking of > > other types of memory (e.g. memfd and ashmem in Android). > > > > Signed-off-by: Kalesh Singh <kaleshsingh@google.com> > > Reviewed-by: Christian König <christian.koenig@amd.com> > > --- > > > > Changes in v2: > > - Add Christian's Reviewed-by > > > > Changes from rfc: > > - Split adding 'size' and 'path' into a separate patches, per Christian > > - Split fdinfo seq_printf into separate lines, per Christian > > - Fix indentation (use tabs) in documentaion, per Randy > > > > Documentation/filesystems/proc.rst | 12 ++++++++++-- > > drivers/dma-buf/dma-buf.c | 1 - > > fs/proc/fd.c | 9 +++++---- > > 3 files changed, 15 insertions(+), 7 deletions(-) > > > ... > > diff --git a/fs/proc/fd.c b/fs/proc/fd.c > > index 913bef0d2a36..464bc3f55759 100644 > > --- a/fs/proc/fd.c > > +++ b/fs/proc/fd.c > > @@ -54,10 +54,11 @@ static int seq_show(struct seq_file *m, void *v) > > if (ret) > > return ret; > > > > - seq_printf(m, "pos:\t%lli\nflags:\t0%o\nmnt_id:\t%i\nino:\t%lu\n", > > - (long long)file->f_pos, f_flags, > > - real_mount(file->f_path.mnt)->mnt_id, > > - file_inode(file)->i_ino); > > + seq_printf(m, "pos:\t%lli\n", (long long)file->f_pos); > > + seq_printf(m, "flags:\t0%o\n", f_flags); > > + seq_printf(m, "mnt_id:\t%i\n", real_mount(file->f_path.mnt)->mnt_id); > > + seq_printf(m, "ino:\t%lu\n", file_inode(file)->i_ino); > > + seq_printf(m, "size:\t%lli\n", (long long)file_inode(file)->i_size); > > Hi Kalesh, > > Any reason not to use i_size_read() here? Hi Brian. Thanks for pointing this out. You are right, we should use i_size_read() here. I'll update in the next version. > > Also not sure if it matters that much for your use case, but something > worth noting at least with shmem is that one can do something like: > > # cat /proc/meminfo | grep Shmem: > Shmem: 764 kB > # xfs_io -fc "falloc -k 0 10m" ./file > # ls -alh file > -rw-------. 1 root root 0 Jun 28 07:22 file > # stat file > File: file > Size: 0 Blocks: 20480 IO Block: 4096 regular empty file > # cat /proc/meminfo | grep Shmem: > Shmem: 11004 kB > > ... where the resulting memory usage isn't reflected in i_size (but is > is in i_blocks/bytes). I tried a similar experiment a few times, but I don't see the same results. In my case, there is not any change in shmem. IIUC the fallocate is allocating the disk space not shared memory. cat /proc/meminfo > meminfo.start xfs_io -fc "falloc -k 0 50m" ./xfs_file cat /proc/meminfo > meminfo.stop tail -n +1 meminfo.st* | grep -i '==\|Shmem:' ==> meminfo.start <== Shmem: 484 kB ==> meminfo.stop <== Shmem: 484 kB ls -lh xfs_file -rw------- 1 root root 0 Jun 28 15:12 xfs_file stat xfs_file File: xfs_file Size: 0 Blocks: 102400 IO Block: 4096 regular empty file Thanks, Kalesh > > Brian > > > > > /* show_fd_locks() never deferences files so a stale value is safe */ > > show_fd_locks(m, file, files); > > -- > > 2.37.0.rc0.161.g10f37bed90-goog > > >
On Wed, Jun 29, 2022 at 5:23 AM Brian Foster <bfoster@redhat.com> wrote: > > On Tue, Jun 28, 2022 at 03:38:02PM -0700, Kalesh Singh wrote: > > On Tue, Jun 28, 2022 at 4:54 AM Brian Foster <bfoster@redhat.com> wrote: > > > > > > On Thu, Jun 23, 2022 at 03:06:06PM -0700, Kalesh Singh wrote: > > > > To be able to account the amount of memory a process is keeping pinned > > > > by open file descriptors add a 'size' field to fdinfo output. > > > > > > > > dmabufs fds already expose a 'size' field for this reason, remove this > > > > and make it a common field for all fds. This allows tracking of > > > > other types of memory (e.g. memfd and ashmem in Android). > > > > > > > > Signed-off-by: Kalesh Singh <kaleshsingh@google.com> > > > > Reviewed-by: Christian König <christian.koenig@amd.com> > > > > --- > > > > > > > > Changes in v2: > > > > - Add Christian's Reviewed-by > > > > > > > > Changes from rfc: > > > > - Split adding 'size' and 'path' into a separate patches, per Christian > > > > - Split fdinfo seq_printf into separate lines, per Christian > > > > - Fix indentation (use tabs) in documentaion, per Randy > > > > > > > > Documentation/filesystems/proc.rst | 12 ++++++++++-- > > > > drivers/dma-buf/dma-buf.c | 1 - > > > > fs/proc/fd.c | 9 +++++---- > > > > 3 files changed, 15 insertions(+), 7 deletions(-) > > > > > ... > > > > > > Also not sure if it matters that much for your use case, but something > > > worth noting at least with shmem is that one can do something like: > > > > > > # cat /proc/meminfo | grep Shmem: > > > Shmem: 764 kB > > > # xfs_io -fc "falloc -k 0 10m" ./file > > > # ls -alh file > > > -rw-------. 1 root root 0 Jun 28 07:22 file > > > # stat file > > > File: file > > > Size: 0 Blocks: 20480 IO Block: 4096 regular empty file > > > # cat /proc/meminfo | grep Shmem: > > > Shmem: 11004 kB > > > > > > ... where the resulting memory usage isn't reflected in i_size (but is > > > is in i_blocks/bytes). > > > > I tried a similar experiment a few times, but I don't see the same > > results. In my case, there is not any change in shmem. IIUC the > > fallocate is allocating the disk space not shared memory. > > > > Sorry, it was implied in my previous test was that I was running against > tmpfs. So regardless of fs, the fallocate keep_size semantics shown in > both cases is as expected: the underlying blocks are allocated and the > inode size is unchanged. > > What wasn't totally clear to me when I read this patch was 1. whether > tmpfs refers to Shmem and 2. whether tmpfs allowed this sort of > operation. The test above seems to confirm both, however, right? E.g., a > more detailed example: > > # mount | grep /tmp > tmpfs on /tmp type tmpfs (rw,nosuid,nodev,seclabel,nr_inodes=1048576,inode64) > # cat /proc/meminfo | grep Shmem: > Shmem: 5300 kB > # xfs_io -fc "falloc -k 0 1g" /tmp/file > # stat /tmp/file > File: /tmp/file > Size: 0 Blocks: 2097152 IO Block: 4096 regular empty file > Device: 22h/34d Inode: 45 Links: 1 > Access: (0600/-rw-------) Uid: ( 0/ root) Gid: ( 0/ root) > Context: unconfined_u:object_r:user_tmp_t:s0 > Access: 2022-06-29 08:04:01.301307154 -0400 > Modify: 2022-06-29 08:04:01.301307154 -0400 > Change: 2022-06-29 08:04:01.451312834 -0400 > Birth: 2022-06-29 08:04:01.301307154 -0400 > # cat /proc/meminfo | grep Shmem: > Shmem: 1053876 kB > # rm -f /tmp/file > # cat /proc/meminfo | grep Shmem: > Shmem: 5300 kB > > So clearly this impacts Shmem.. was your test run against tmpfs or some > other (disk based) fs? Hi Brian, Thanks for clarifying. My issue was tmpfs not mounted at /tmp in my system: ==> meminfo.start <== Shmem: 572 kB ==> meminfo.stop <== Shmem: 51688 kB > > FWIW, I don't have any objection to exposing inode size if it's commonly > useful information. My feedback was more just an fyi that i_size doesn't > necessarily reflect underlying space consumption (whether it's memory or > disk space) in more generic cases, because it sounds like that is really > what you're after here. The opposite example to the above would be > something like an 'xfs_io -fc "truncate 1t" /tmp/file', which shows a > 1TB inode size with zero additional shmem usage.
On Thu, Jun 30, 2022 at 5:03 AM Brian Foster <bfoster@redhat.com> wrote: > > On Thu, Jun 30, 2022 at 07:48:46AM -0400, Brian Foster wrote: > > On Wed, Jun 29, 2022 at 01:43:11PM -0700, Kalesh Singh wrote: > > > On Wed, Jun 29, 2022 at 5:23 AM Brian Foster <bfoster@redhat.com> wrote: > > > > > > > > On Tue, Jun 28, 2022 at 03:38:02PM -0700, Kalesh Singh wrote: > > > > > On Tue, Jun 28, 2022 at 4:54 AM Brian Foster <bfoster@redhat.com> wrote: > > > > > > > > > > > > On Thu, Jun 23, 2022 at 03:06:06PM -0700, Kalesh Singh wrote: > > > > > > > To be able to account the amount of memory a process is keeping pinned > > > > > > > by open file descriptors add a 'size' field to fdinfo output. > > > > > > > > > > > > > > dmabufs fds already expose a 'size' field for this reason, remove this > > > > > > > and make it a common field for all fds. This allows tracking of > > > > > > > other types of memory (e.g. memfd and ashmem in Android). > > > > > > > > > > > > > > Signed-off-by: Kalesh Singh <kaleshsingh@google.com> > > > > > > > Reviewed-by: Christian König <christian.koenig@amd.com> > > > > > > > --- > > > > > > > > > > > > > > Changes in v2: > > > > > > > - Add Christian's Reviewed-by > > > > > > > > > > > > > > Changes from rfc: > > > > > > > - Split adding 'size' and 'path' into a separate patches, per Christian > > > > > > > - Split fdinfo seq_printf into separate lines, per Christian > > > > > > > - Fix indentation (use tabs) in documentaion, per Randy > > > > > > > > > > > > > > Documentation/filesystems/proc.rst | 12 ++++++++++-- > > > > > > > drivers/dma-buf/dma-buf.c | 1 - > > > > > > > fs/proc/fd.c | 9 +++++---- > > > > > > > 3 files changed, 15 insertions(+), 7 deletions(-) > > > > > > > > > > > ... > > > > > > > > > > > > Also not sure if it matters that much for your use case, but something > > > > > > worth noting at least with shmem is that one can do something like: > > > > > > > > > > > > # cat /proc/meminfo | grep Shmem: > > > > > > Shmem: 764 kB > > > > > > # xfs_io -fc "falloc -k 0 10m" ./file > > > > > > # ls -alh file > > > > > > -rw-------. 1 root root 0 Jun 28 07:22 file > > > > > > # stat file > > > > > > File: file > > > > > > Size: 0 Blocks: 20480 IO Block: 4096 regular empty file > > > > > > # cat /proc/meminfo | grep Shmem: > > > > > > Shmem: 11004 kB > > > > > > > > > > > > ... where the resulting memory usage isn't reflected in i_size (but is > > > > > > is in i_blocks/bytes). > > > > > > > > > > I tried a similar experiment a few times, but I don't see the same > > > > > results. In my case, there is not any change in shmem. IIUC the > > > > > fallocate is allocating the disk space not shared memory. > > > > > > > > > > > > > Sorry, it was implied in my previous test was that I was running against > > > > tmpfs. So regardless of fs, the fallocate keep_size semantics shown in > > > > both cases is as expected: the underlying blocks are allocated and the > > > > inode size is unchanged. > > > > > > > > What wasn't totally clear to me when I read this patch was 1. whether > > > > tmpfs refers to Shmem and 2. whether tmpfs allowed this sort of > > > > operation. The test above seems to confirm both, however, right? E.g., a > > > > more detailed example: > > > > > > > > # mount | grep /tmp > > > > tmpfs on /tmp type tmpfs (rw,nosuid,nodev,seclabel,nr_inodes=1048576,inode64) > > > > # cat /proc/meminfo | grep Shmem: > > > > Shmem: 5300 kB > > > > # xfs_io -fc "falloc -k 0 1g" /tmp/file > > > > # stat /tmp/file > > > > File: /tmp/file > > > > Size: 0 Blocks: 2097152 IO Block: 4096 regular empty file > > > > Device: 22h/34d Inode: 45 Links: 1 > > > > Access: (0600/-rw-------) Uid: ( 0/ root) Gid: ( 0/ root) > > > > Context: unconfined_u:object_r:user_tmp_t:s0 > > > > Access: 2022-06-29 08:04:01.301307154 -0400 > > > > Modify: 2022-06-29 08:04:01.301307154 -0400 > > > > Change: 2022-06-29 08:04:01.451312834 -0400 > > > > Birth: 2022-06-29 08:04:01.301307154 -0400 > > > > # cat /proc/meminfo | grep Shmem: > > > > Shmem: 1053876 kB > > > > # rm -f /tmp/file > > > > # cat /proc/meminfo | grep Shmem: > > > > Shmem: 5300 kB > > > > > > > > So clearly this impacts Shmem.. was your test run against tmpfs or some > > > > other (disk based) fs? > > > > > > Hi Brian, > > > > > > Thanks for clarifying. My issue was tmpfs not mounted at /tmp in my system: > > > > > > ==> meminfo.start <== > > > Shmem: 572 kB > > > ==> meminfo.stop <== > > > Shmem: 51688 kB > > > > > > > Ok, makes sense. > > > > > > > > > > FWIW, I don't have any objection to exposing inode size if it's commonly > > > > useful information. My feedback was more just an fyi that i_size doesn't > > > > necessarily reflect underlying space consumption (whether it's memory or > > > > disk space) in more generic cases, because it sounds like that is really > > > > what you're after here. The opposite example to the above would be > > > > something like an 'xfs_io -fc "truncate 1t" /tmp/file', which shows a > > > > 1TB inode size with zero additional shmem usage. > > > > > > From these cases, it seems the more generic way to do this is by > > > calculating the actual size consumed using the blocks. (i_blocks * > > > 512). So in the latter example 'xfs_io -fc "truncate 1t" /tmp/file' > > > the size consumed would be zero. Let me know if it sounds ok to you > > > and I can repost the updated version. > > > > > > > That sounds a bit more useful to me if you're interested in space usage, > > or at least I don't have a better idea for you. ;) > > > > One thing to note is that I'm not sure whether all fs' use i_blocks > > reliably. E.g., XFS populates stat->blocks via a separate block counter > > in the XFS specific inode structure (see xfs_vn_getattr()). A bunch of > > other fs' seem to touch it so perhaps that is just an outlier. You could > > consider fixing that up, perhaps make a ->getattr() call to avoid it, or > > just use the field directly if it's useful enough as is and there are no > > other objections. Something to think about anyways.. > > Hi Brian, Thanks for pointing it out. Let me take a look into the xfs case. > > Oh, I wonder if you're looking for similar "file rss" information this > series wants to collect/expose..? > > https://lore.kernel.org/linux-fsdevel/20220624080444.7619-1-christian.koenig@amd.com/#r Christian's series seems to have some overlap with what we want to achieve here. IIUC it exposes the information on the per process granularity. Perhaps if that approach is agreed on, I think we can use the file_rss() f_op to expose the per file size in the fdinfo for the cases where the i_blocks are unreliable. Thanks, Kalesh > > Brian > > > Brian > > > > > Thanks, > > > Kalesh > > > > > > > > > > > Brian > > > > > > > > > cat /proc/meminfo > meminfo.start > > > > > xfs_io -fc "falloc -k 0 50m" ./xfs_file > > > > > cat /proc/meminfo > meminfo.stop > > > > > tail -n +1 meminfo.st* | grep -i '==\|Shmem:' > > > > > > > > > > ==> meminfo.start <== > > > > > Shmem: 484 kB > > > > > ==> meminfo.stop <== > > > > > Shmem: 484 kB > > > > > > > > > > ls -lh xfs_file > > > > > -rw------- 1 root root 0 Jun 28 15:12 xfs_file > > > > > > > > > > stat xfs_file > > > > > File: xfs_file > > > > > Size: 0 Blocks: 102400 IO Block: 4096 regular empty file > > > > > > > > > > Thanks, > > > > > Kalesh > > > > > > > > > > > > > > > > > Brian > > > > > > > > > > > > > > > > > > > > /* show_fd_locks() never deferences files so a stale value is safe */ > > > > > > > show_fd_locks(m, file, files); > > > > > > > -- > > > > > > > 2.37.0.rc0.161.g10f37bed90-goog > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > To unsubscribe from this group and stop receiving emails from it, send an email to kernel-team+unsubscribe@android.com. > > > > > > > >
Hi all, This is v2 of the fdinfo patches. The main update is adding path field only for files with anon inodes. Rebased on 5.19-rc3. The previous cover letter is copied below for convenience. Thanks, Kalesh ----------- Processes can pin shared memory by keeping a handle to it through a file descriptor; for instance dmabufs, memfd, and ashmem (in Android). In the case of a memory leak, to identify the process pinning the memory, userspace needs to: - Iterate the /proc/<pid>/fd/* for each process - Do a readlink on each entry to identify the type of memory from the file path. - stat() each entry to get the size of the memory. The file permissions on /proc/<pid>/fd/* only allows for the owner or root to perform the operations above; and so is not suitable for capturing the system-wide state in a production environment. This issue was addressed for dmabufs by making /proc/*/fdinfo/* accessible to a process with PTRACE_MODE_READ_FSCREDS credentials[1] To allow the same kind of tracking for other types of shared memory, add the following fields to /proc/<pid>/fdinfo/<fd>: path - This allows identifying the type of memory based on common prefixes: e.g. "/memfd...", "/dmabuf...", "/dev/ashmem..." This was not an issued when dmabuf tracking was introduced because the exp_name field of dmabuf fdinfo could be used to distinguish dmabuf fds from other types. size - To track the amount of memory that is being pinned. dmabufs expose size as an additional field in fdinfo. Remove this and make it a common field for all fds. Access to /proc/<pid>/fdinfo is governed by PTRACE_MODE_READ_FSCREDS -- the same as for /proc/<pid>/maps which also exposes the path and size for mapped memory regions. This allows for a system process with PTRACE_MODE_READ_FSCREDS to account the pinned per-process memory via fdinfo. Kalesh Singh (2): procfs: Add 'size' to /proc/<pid>/fdinfo/ procfs: Add 'path' to /proc/<pid>/fdinfo/ Documentation/filesystems/proc.rst | 22 ++++++++++++++++++++-- drivers/dma-buf/dma-buf.c | 1 - fs/libfs.c | 9 +++++++++ fs/proc/fd.c | 18 ++++++++++++++---- include/linux/fs.h | 1 + 5 files changed, 44 insertions(+), 7 deletions(-) base-commit: a111daf0c53ae91e71fd2bfe7497862d14132e3e