| Message ID | 20230522070905.16773-2-ying.huang@intel.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | swap: cleanup get/put_swap_device() usage | expand |
On 22.05.23 09:09, Huang Ying wrote: > __swap_count() is called in do_swap_page() only, which encloses the > call site with get/put_swap_device() already. > > Signed-off-by: "Huang, Ying" <ying.huang@intel.com> > Cc: David Hildenbrand <david@redhat.com> > Cc: Hugh Dickins <hughd@google.com> > Cc: Johannes Weiner <hannes@cmpxchg.org> > Cc: Matthew Wilcox <willy@infradead.org> > Cc: Michal Hocko <mhocko@suse.com> > Cc: Minchan Kim <minchan@kernel.org> > Cc: Tim Chen <tim.c.chen@linux.intel.com> > Cc: Yang Shi <shy828301@gmail.com> > Cc: Yu Zhao <yuzhao@google.com> > --- > mm/swapfile.c | 10 ++-------- > 1 file changed, 2 insertions(+), 8 deletions(-) > > diff --git a/mm/swapfile.c b/mm/swapfile.c > index 274bbf797480..8419cba9c192 100644 > --- a/mm/swapfile.c > +++ b/mm/swapfile.c > @@ -1432,16 +1432,10 @@ void swapcache_free_entries(swp_entry_t *entries, int n) > > int __swap_count(swp_entry_t entry) > { > - struct swap_info_struct *si; > + struct swap_info_struct *si = swp_swap_info(entry); > pgoff_t offset = swp_offset(entry); > - int count = 0; > > - si = get_swap_device(entry); > - if (si) { > - count = swap_count(si->swap_map[offset]); > - put_swap_device(si); > - } > - return count; > + return swap_count(si->swap_map[offset]); > } > > /* That locking was added in eb085574a752 ("mm, swap: fix race between swapoff and some swap operations"). Before 2799e77529c ("swap: fix do_swap_page() race with swapoff") added the get_swap_device() to do_swap_page(). Reviewed-by: David Hildenbrand <david@redhat.com>
On Mon, May 22, 2023 at 12:09 AM Huang Ying <ying.huang@intel.com> wrote: > > __swap_count() is called in do_swap_page() only, which encloses the > call site with get/put_swap_device() already. > > Signed-off-by: "Huang, Ying" <ying.huang@intel.com> > Cc: David Hildenbrand <david@redhat.com> > Cc: Hugh Dickins <hughd@google.com> > Cc: Johannes Weiner <hannes@cmpxchg.org> > Cc: Matthew Wilcox <willy@infradead.org> > Cc: Michal Hocko <mhocko@suse.com> > Cc: Minchan Kim <minchan@kernel.org> > Cc: Tim Chen <tim.c.chen@linux.intel.com> > Cc: Yang Shi <shy828301@gmail.com> > Cc: Yu Zhao <yuzhao@google.com> > --- > mm/swapfile.c | 10 ++-------- > 1 file changed, 2 insertions(+), 8 deletions(-) > > diff --git a/mm/swapfile.c b/mm/swapfile.c > index 274bbf797480..8419cba9c192 100644 > --- a/mm/swapfile.c > +++ b/mm/swapfile.c > @@ -1432,16 +1432,10 @@ void swapcache_free_entries(swp_entry_t *entries, int n) > nit: I would add a comment here that the caller needs get/put_swap_device(). Reviewed-by: Yosry Ahmed <yosryahmed@google.com> > int __swap_count(swp_entry_t entry) > { > - struct swap_info_struct *si; > + struct swap_info_struct *si = swp_swap_info(entry); > pgoff_t offset = swp_offset(entry); > - int count = 0; > > - si = get_swap_device(entry); > - if (si) { > - count = swap_count(si->swap_map[offset]); > - put_swap_device(si); > - } > - return count; > + return swap_count(si->swap_map[offset]); > } > > /* > -- > 2.39.2 > >
Yosry Ahmed <yosryahmed@google.com> writes: > On Mon, May 22, 2023 at 12:09 AM Huang Ying <ying.huang@intel.com> wrote: >> >> __swap_count() is called in do_swap_page() only, which encloses the >> call site with get/put_swap_device() already. >> >> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> >> Cc: David Hildenbrand <david@redhat.com> >> Cc: Hugh Dickins <hughd@google.com> >> Cc: Johannes Weiner <hannes@cmpxchg.org> >> Cc: Matthew Wilcox <willy@infradead.org> >> Cc: Michal Hocko <mhocko@suse.com> >> Cc: Minchan Kim <minchan@kernel.org> >> Cc: Tim Chen <tim.c.chen@linux.intel.com> >> Cc: Yang Shi <shy828301@gmail.com> >> Cc: Yu Zhao <yuzhao@google.com> >> --- >> mm/swapfile.c | 10 ++-------- >> 1 file changed, 2 insertions(+), 8 deletions(-) >> >> diff --git a/mm/swapfile.c b/mm/swapfile.c >> index 274bbf797480..8419cba9c192 100644 >> --- a/mm/swapfile.c >> +++ b/mm/swapfile.c >> @@ -1432,16 +1432,10 @@ void swapcache_free_entries(swp_entry_t *entries, int n) >> > > nit: I would add a comment here that the caller needs get/put_swap_device(). It's default behavior to call get/put_swap_device() in the caller for all almost all swap functions. I would rather comment the swap functions needn't to do that, as the comments for read_swap_cache_async() in [2/5]. > Reviewed-by: Yosry Ahmed <yosryahmed@google.com> Thanks! >> int __swap_count(swp_entry_t entry) >> { >> - struct swap_info_struct *si; >> + struct swap_info_struct *si = swp_swap_info(entry); >> pgoff_t offset = swp_offset(entry); >> - int count = 0; >> >> - si = get_swap_device(entry); >> - if (si) { >> - count = swap_count(si->swap_map[offset]); >> - put_swap_device(si); >> - } >> - return count; >> + return swap_count(si->swap_map[offset]); >> } >> >> /* Best Regards, Huang, Ying
On Mon, May 22, 2023 at 6:48 PM Huang, Ying <ying.huang@intel.com> wrote: > > Yosry Ahmed <yosryahmed@google.com> writes: > > > On Mon, May 22, 2023 at 12:09 AM Huang Ying <ying.huang@intel.com> wrote: > >> > >> __swap_count() is called in do_swap_page() only, which encloses the > >> call site with get/put_swap_device() already. > >> > >> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> > >> Cc: David Hildenbrand <david@redhat.com> > >> Cc: Hugh Dickins <hughd@google.com> > >> Cc: Johannes Weiner <hannes@cmpxchg.org> > >> Cc: Matthew Wilcox <willy@infradead.org> > >> Cc: Michal Hocko <mhocko@suse.com> > >> Cc: Minchan Kim <minchan@kernel.org> > >> Cc: Tim Chen <tim.c.chen@linux.intel.com> > >> Cc: Yang Shi <shy828301@gmail.com> > >> Cc: Yu Zhao <yuzhao@google.com> > >> --- > >> mm/swapfile.c | 10 ++-------- > >> 1 file changed, 2 insertions(+), 8 deletions(-) > >> > >> diff --git a/mm/swapfile.c b/mm/swapfile.c > >> index 274bbf797480..8419cba9c192 100644 > >> --- a/mm/swapfile.c > >> +++ b/mm/swapfile.c > >> @@ -1432,16 +1432,10 @@ void swapcache_free_entries(swp_entry_t *entries, int n) > >> > > > > nit: I would add a comment here that the caller needs get/put_swap_device(). > > It's default behavior to call get/put_swap_device() in the caller for > all almost all swap functions. I would rather comment the swap > functions needn't to do that, as the comments for > read_swap_cache_async() in [2/5]. Fair enough. The comment that you added above get_swap_device() states that all swap-related functions should have some sort of protection against swapoff, so I guess that's sufficient. My concern is that sometimes people don't know where to look, and having a comment above the function might be helpful. I do agree though that having a comment above ~all swap-related functions pointing to the comment above get_swap_device() is too much. > > > Reviewed-by: Yosry Ahmed <yosryahmed@google.com> > > Thanks! > > >> int __swap_count(swp_entry_t entry) > >> { > >> - struct swap_info_struct *si; > >> + struct swap_info_struct *si = swp_swap_info(entry); > >> pgoff_t offset = swp_offset(entry); > >> - int count = 0; > >> > >> - si = get_swap_device(entry); > >> - if (si) { > >> - count = swap_count(si->swap_map[offset]); > >> - put_swap_device(si); > >> - } > >> - return count; > >> + return swap_count(si->swap_map[offset]); > >> } > >> > >> /* > > Best Regards, > Huang, Ying
diff --git a/mm/swapfile.c b/mm/swapfile.c index 274bbf797480..8419cba9c192 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1432,16 +1432,10 @@ void swapcache_free_entries(swp_entry_t *entries, int n) int __swap_count(swp_entry_t entry) { - struct swap_info_struct *si; + struct swap_info_struct *si = swp_swap_info(entry); pgoff_t offset = swp_offset(entry); - int count = 0; - si = get_swap_device(entry); - if (si) { - count = swap_count(si->swap_map[offset]); - put_swap_device(si); - } - return count; + return swap_count(si->swap_map[offset]); } /*
__swap_count() is called in do_swap_page() only, which encloses the call site with get/put_swap_device() already. Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Yang Shi <shy828301@gmail.com> Cc: Yu Zhao <yuzhao@google.com> --- mm/swapfile.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-)