I think this patch isn't need at all. You can directly read total_swap_pages variable in TTM. Because the variable is not exported by EXPORT_SYMBOL_GPL. So direct using will result in: "WARNING: "total_swap_pages" [drivers/gpu/drm/ttm/ttm.ko] undefined!". Thanks Roger(Hongbo.He) -----Original Message----- From: dri-devel [mailto:dri-devel-bounces@xxxxxxxxxxxxxxxxxxxxx] On Behalf Of Chunming Zhou Sent: Wednesday, January 31, 2018 3:15 PM To: He, Roger <Hongbo.He@xxxxxxx>; dri-devel@xxxxxxxxxxxxxxxxxxxxx Cc: linux-mm@xxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Koenig, Christian <Christian.Koenig@xxxxxxx> Subject: Re: [PATCH] mm/swap: add function get_total_swap_pages to expose total_swap_pages Hi Roger, I think this patch isn't need at all. You can directly read total_swap_pages variable in TTM. See the comment: /* protected with swap_lock. reading in vm_swap_full() doesn't need lock */ long total_swap_pages; there are many places using it directly, you just couldn't change its value. Reading it doesn't need lock. Regards, David Zhou On 2018年01月29日 16:29, Roger He wrote: > ttm module needs it to determine its internal parameter setting. > > Signed-off-by: Roger He <Hongbo.He@xxxxxxx> > --- > include/linux/swap.h | 6 ++++++ > mm/swapfile.c | 15 +++++++++++++++ > 2 files changed, 21 insertions(+) > > diff --git a/include/linux/swap.h b/include/linux/swap.h > index c2b8128..708d66f 100644 > --- a/include/linux/swap.h > +++ b/include/linux/swap.h > @@ -484,6 +484,7 @@ extern int try_to_free_swap(struct page *); > struct backing_dev_info; > extern int init_swap_address_space(unsigned int type, unsigned long nr_pages); > extern void exit_swap_address_space(unsigned int type); > +extern long get_total_swap_pages(void); > > #else /* CONFIG_SWAP */ > > @@ -516,6 +517,11 @@ static inline void show_swap_cache_info(void) > { > } > > +long get_total_swap_pages(void) > +{ > + return 0; > +} > + > #define free_swap_and_cache(e) ({(is_migration_entry(e) || is_device_private_entry(e));}) > #define swapcache_prepare(e) ({(is_migration_entry(e) || is_device_private_entry(e));}) > > diff --git a/mm/swapfile.c b/mm/swapfile.c > index 3074b02..a0062eb 100644 > --- a/mm/swapfile.c > +++ b/mm/swapfile.c > @@ -98,6 +98,21 @@ static atomic_t proc_poll_event = ATOMIC_INIT(0); > > atomic_t nr_rotate_swap = ATOMIC_INIT(0); > > +/* > + * expose this value for others use > + */ > +long get_total_swap_pages(void) > +{ > + long ret; > + > + spin_lock(&swap_lock); > + ret = total_swap_pages; > + spin_unlock(&swap_lock); > + > + return ret; > +} > +EXPORT_SYMBOL_GPL(get_total_swap_pages); > + > static inline unsigned char swap_count(unsigned char ent) > { > return ent & ~SWAP_HAS_CACHE; /* may include SWAP_HAS_CONT flag */ _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
