Re: [PATCH v3] ucounts: add missing data type changes

[Naresh Kamboju]

On Fri, 6 Aug 2021 at 00:56, Nathan Chancellor <nathan@xxxxxxxxxx> wrote:
>
> On 8/5/2021 9:48 AM, Eric W. Biederman wrote:
> > Nathan Chancellor <nathan@xxxxxxxxxx> writes:
> >
> >> Hi Eric,
> >>
> >> On 8/4/2021 12:47 PM, Eric W. Biederman wrote:
> >>> Nathan Chancellor <nathan@xxxxxxxxxx> writes:
> >>>
> >>>> On Fri, Jul 30, 2021 at 08:28:54AM +0200, Sven Schnelle wrote:
> >>>>> commit f9c82a4ea89c3 ("Increase size of ucounts to atomic_long_t")
> >>>>> changed the data type of ucounts/ucounts_max to long, but missed to
> >>>>> adjust a few other places. This is noticeable on big endian platforms
> >>>>> from user space because the /proc/sys/user/max_*_names files all
> >>>>> contain 0.
> >>>>>
> >>>>> Fixes: f9c82a4ea89c ("Increase size of ucounts to atomic_long_t")
> >>>>> Signed-off-by: Sven Schnelle <svens@xxxxxxxxxxxxx>
> >>>>
> >>>> This patch in -next as commit e43fc41d1f7f ("ucounts: add missing data type
> >>>> changes") causes Windows Subsystem for Linux to fail to start:

On Linux next-20210802..next-20210805 we have been noticing
that LTP syscalls inotify06 test case getting failed all architectures.

BAD:
  Linux next-20210802
  inotify06.c:57: TBROK: Failed to close FILE
'/proc/sys/fs/inotify/max_user_instances': EINVAL (22)
  inotify06.c:107: TWARN: Failed to close FILE
'/proc/sys/fs/inotify/max_user_instances': EINVAL (22)

GOOD:
  Linux next-20210730
  inotify06.c:92: TPASS: kernel survived inotify beating

Investigation:
Following changes found between good and bad Linux next tags under fs/notify
git log --oneline --stat next-20210730..next-20210802 fs/notify
e43fc41d1f7f ucounts: add missing data type changes
 fs/notify/fanotify/fanotify_user.c | 10 ++++++----
 fs/notify/inotify/inotify_user.c   | 10 ++++++----
 2 files changed, 12 insertions(+), 8 deletions(-)

Conclusion:
We have confirmed this patch caused the LTP syscalls inotify06 test failure.

After applying your proposed fix patch [1] the reported test getting pass.
However, I have to run full test plan to confirm this do not cause regressions.

Tested-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>

[1] https://lore.kernel.org/lkml/87v94jalck.fsf@disp2133/


> > diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> > index 6576657a1a25..28b67cb9458d 100644
> > --- a/fs/notify/fanotify/fanotify_user.c
> > +++ b/fs/notify/fanotify/fanotify_user.c
> > @@ -54,6 +54,9 @@ static int fanotify_max_queued_events __read_mostly;
> >
> >   #include <linux/sysctl.h>
> >
> > +static long ft_zero = 0;
> > +static long ft_int_max = INT_MAX;
> > +
> >   struct ctl_table fanotify_table[] = {
> >       {
> >               .procname       = "max_user_groups",
> > @@ -61,8 +64,8 @@ struct ctl_table fanotify_table[] = {
> >               .maxlen         = sizeof(long),
> >               .mode           = 0644,
> >               .proc_handler   = proc_doulongvec_minmax,
> > -             .extra1         = SYSCTL_ZERO,
> > -             .extra2         = SYSCTL_INT_MAX,
> > +             .extra1         = &ft_zero,
> > +             .extra2         = &ft_int_max,
> >       },
> >       {
> >               .procname       = "max_user_marks",
> > @@ -70,8 +73,8 @@ struct ctl_table fanotify_table[] = {
> >               .maxlen         = sizeof(long),
> >               .mode           = 0644,
> >               .proc_handler   = proc_doulongvec_minmax,
> > -             .extra1         = SYSCTL_ZERO,
> > -             .extra2         = SYSCTL_INT_MAX,
> > +             .extra1         = &ft_zero,
> > +             .extra2         = &ft_int_max,
> >       },
> >       {
> >               .procname       = "max_queued_events",
> > diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
> > index 55fe7cdea2fb..62051247f6d2 100644
> > --- a/fs/notify/inotify/inotify_user.c
> > +++ b/fs/notify/inotify/inotify_user.c
> > @@ -55,6 +55,9 @@ struct kmem_cache *inotify_inode_mark_cachep __read_mostly;
> >
> >   #include <linux/sysctl.h>
> >
> > +static long it_zero = 0;
> > +static long it_int_max = INT_MAX;
> > +
> >   struct ctl_table inotify_table[] = {
> >       {
> >               .procname       = "max_user_instances",
> > @@ -62,8 +65,8 @@ struct ctl_table inotify_table[] = {
> >               .maxlen         = sizeof(long),
> >               .mode           = 0644,
> >               .proc_handler   = proc_doulongvec_minmax,
> > -             .extra1         = SYSCTL_ZERO,
> > -             .extra2         = SYSCTL_INT_MAX,
> > +             .extra1         = &it_zero,
> > +             .extra2         = &it_int_max,
> >       },
> >       {
> >               .procname       = "max_user_watches",
> > @@ -71,8 +74,8 @@ struct ctl_table inotify_table[] = {
> >               .maxlen         = sizeof(long),
> >               .mode           = 0644,
> >               .proc_handler   = proc_doulongvec_minmax,
> > -             .extra1         = SYSCTL_ZERO,
> > -             .extra2         = SYSCTL_INT_MAX,
> > +             .extra1         = &it_zero,
> > +             .extra2         = &it_int_max,
> >       },
> >       {
> >               .procname       = "max_queued_events",
> > diff --git a/kernel/ucount.c b/kernel/ucount.c
> > index 260ae7da815f..bb51849e6375 100644
> > --- a/kernel/ucount.c
> > +++ b/kernel/ucount.c
> > @@ -58,14 +58,17 @@ static struct ctl_table_root set_root = {
> >       .permissions = set_permissions,
> >   };
> >
> > +static long ue_zero = 0;
> > +static long ue_int_max = INT_MAX;
> > +
> >   #define UCOUNT_ENTRY(name)                                  \
> >       {                                                       \
> >               .procname       = name,                         \
> >               .maxlen         = sizeof(long),                 \
> >               .mode           = 0644,                         \
> >               .proc_handler   = proc_doulongvec_minmax,       \
> > -             .extra1         = SYSCTL_ZERO,                  \
> > -             .extra2         = SYSCTL_INT_MAX,               \
> > +             .extra1         = &ue_zero,                     \
> > +             .extra2         = &ue_int_max,                  \
> >       }
> >   static struct ctl_table user_table[] = {
> >       UCOUNT_ENTRY("max_user_namespaces"),


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