Michal has posted the same patch few days ago http://lkml.kernel.org/r/20190417120347.15397-1-mkoutny@xxxxxxxx On Thu 18-04-19 14:58:27, Laurent Dufour wrote: > The commit 88aa7cc688d4 ("mm: introduce arg_lock to protect arg_start|end > and env_start|end in mm_struct") introduce the spinlock arg_lock to protect > the arg_* and env_* field of the mm_struct structure. > > While reading the code, I found that this new spinlock was not used in > get_cmdline() to protect access to these fields. > > Fixing this even if there is no issue reported yet for this. > > Fixes: 88aa7cc688d4 ("mm: introduce arg_lock to protect arg_start|end and env_start|end in mm_struct") > Cc: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx> > Signed-off-by: Laurent Dufour <ldufour@xxxxxxxxxxxxx> > --- > mm/util.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/util.c b/mm/util.c > index 05a464929b3e..789760c3028b 100644 > --- a/mm/util.c > +++ b/mm/util.c > @@ -758,12 +758,12 @@ int get_cmdline(struct task_struct *task, char *buffer, int buflen) > if (!mm->arg_end) > goto out_mm; /* Shh! No looking before we're done */ > > - down_read(&mm->mmap_sem); > + spin_lock(&mm->arg_lock); > arg_start = mm->arg_start; > arg_end = mm->arg_end; > env_start = mm->env_start; > env_end = mm->env_end; > - up_read(&mm->mmap_sem); > + spin_unlock(&mm->arg_lock); > > len = arg_end - arg_start; > > -- > 2.21.0 -- Michal Hocko SUSE Labs
