| Message ID | 20210408130820.48233-4-linmiaohe@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | close various race windows for swap | expand |
Miaohe Lin <linmiaohe@huawei.com> writes: > The function get_shadow_from_swap_cache() can race with swapoff, though > it's only called by do_swap_page() now. > > Fixes: aae466b0052e ("mm/swap: implement workingset detection for anonymous LRU") > Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> This is unnecessary. The only caller has guaranteed the swap device from swapoff. Best Regards, Huang, Ying > --- > mm/swap_state.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/mm/swap_state.c b/mm/swap_state.c > index 272ea2108c9d..709c260d644a 100644 > --- a/mm/swap_state.c > +++ b/mm/swap_state.c > @@ -83,11 +83,14 @@ void show_swap_cache_info(void) > > void *get_shadow_from_swap_cache(swp_entry_t entry) > { > - struct address_space *address_space = swap_address_space(entry); > - pgoff_t idx = swp_offset(entry); > + struct swap_info_struct *si; > struct page *page; > > - page = xa_load(&address_space->i_pages, idx); > + si = get_swap_device(entry); > + if (!si) > + return NULL; > + page = xa_load(&swap_address_space(entry)->i_pages, swp_offset(entry)); > + put_swap_device(si); > if (xa_is_value(page)) > return page; > return NULL;
On 2021/4/13 9:33, Huang, Ying wrote: > Miaohe Lin <linmiaohe@huawei.com> writes: > >> The function get_shadow_from_swap_cache() can race with swapoff, though >> it's only called by do_swap_page() now. >> >> Fixes: aae466b0052e ("mm/swap: implement workingset detection for anonymous LRU") >> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> > > This is unnecessary. The only caller has guaranteed the swap device > from swapoff Ok. This patch is just in case get_shadow_from_swap_cache() would be called from elsewhere someday. It's unnecessary and can be dropped now . > > Best Regards, > Huang, Ying > >> --- >> mm/swap_state.c | 9 ++++++--- >> 1 file changed, 6 insertions(+), 3 deletions(-) >> >> diff --git a/mm/swap_state.c b/mm/swap_state.c >> index 272ea2108c9d..709c260d644a 100644 >> --- a/mm/swap_state.c >> +++ b/mm/swap_state.c >> @@ -83,11 +83,14 @@ void show_swap_cache_info(void) >> >> void *get_shadow_from_swap_cache(swp_entry_t entry) >> { >> - struct address_space *address_space = swap_address_space(entry); >> - pgoff_t idx = swp_offset(entry); >> + struct swap_info_struct *si; >> struct page *page; >> >> - page = xa_load(&address_space->i_pages, idx); >> + si = get_swap_device(entry); >> + if (!si) >> + return NULL; >> + page = xa_load(&swap_address_space(entry)->i_pages, swp_offset(entry)); >> + put_swap_device(si); >> if (xa_is_value(page)) >> return page; >> return NULL; > > . >
diff --git a/mm/swap_state.c b/mm/swap_state.c index 272ea2108c9d..709c260d644a 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -83,11 +83,14 @@ void show_swap_cache_info(void) void *get_shadow_from_swap_cache(swp_entry_t entry) { - struct address_space *address_space = swap_address_space(entry); - pgoff_t idx = swp_offset(entry); + struct swap_info_struct *si; struct page *page; - page = xa_load(&address_space->i_pages, idx); + si = get_swap_device(entry); + if (!si) + return NULL; + page = xa_load(&swap_address_space(entry)->i_pages, swp_offset(entry)); + put_swap_device(si); if (xa_is_value(page)) return page; return NULL;
The function get_shadow_from_swap_cache() can race with swapoff, though it's only called by do_swap_page() now. Fixes: aae466b0052e ("mm/swap: implement workingset detection for anonymous LRU") Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> --- mm/swap_state.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)