flags

The flags field records various attributes corresponding to a process. Each bit in the field corresponds to various stages in the lifetime of a process. Per-process flags are defined in <linux/sched.h>:

#define PF_EXITING           /* getting shut down */
#define PF_EXITPIDONE        /* pi exit done on shut down */
#define PF_VCPU              /* I'm a virtual CPU */
#define PF_WQ_WORKER         /* I'm a workqueue worker */
#define PF_FORKNOEXEC        /* forked but didn't exec */
#define PF_MCE_PROCESS       /* process policy on mce errors */
#define PF_SUPERPRIV         /* used super-user privileges */
#define PF_DUMPCORE          /* dumped core */
#define PF_SIGNALED          /* killed by a signal */
#define PF_MEMALLOC          /* Allocating memory */
#define PF_NPROC_EXCEEDED    /* set_user noticed that RLIMIT_NPROC was exceeded */
#define PF_USED_MATH         /* if unset the fpu must be initialized before use */
#define PF_USED_ASYNC        /* used async_schedule*(), used by module init */
#define PF_NOFREEZE          /* this thread should not be frozen */
#define PF_FROZEN            /* frozen for system suspend */
#define PF_FSTRANS           /* inside a filesystem transaction */
#define PF_KSWAPD            /* I am kswapd */
#define PF_MEMALLOC_NOIO0    /* Allocating memory without IO involved */
#define PF_LESS_THROTTLE     /* Throttle me less: I clean memory */
#define PF_KTHREAD           /* I am a kernel thread */
#define PF_RANDOMIZE         /* randomize virtual address space */
#define PF_SWAPWRITE         /* Allowed to write to swap */
#define PF_NO_SETAFFINITY    /* Userland is not allowed to meddle with cpus_allowed */
#define PF_MCE_EARLY         /* Early kill for mce process policy */
#define PF_MUTEX_TESTER      /* Thread belongs to the rt mutex tester */
#define PF_FREEZER_SKIP      /* Freezer should not count it as freezable */
#define PF_SUSPEND_TASK      /* this thread called freeze_processes and should not be frozen */