| Message ID | 20220429064051.61552-4-linmiaohe@huawei.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | A few fixup patches for z3fold | expand |
On Fri, Apr 29, 2022 at 8:41 AM Miaohe Lin <linmiaohe@huawei.com> wrote: > > Currently if z3fold couldn't find an unbuddied page it would first try to > pull a page off the stale list. But this approach is problematic. If init > z3fold page fails later, the page should be freed via free_z3fold_page to > clean up the relevant resource instead of using __free_page directly. And > if page is successfully reused, it will BUG_ON later in __SetPageMovable > because it's already non-lru movable page, i.e. PAGE_MAPPING_MOVABLE is > already set in page->mapping. In order to fix all of these issues, we can > simply remove the buggy use of stale list for allocation because can_sleep > should always be false and we never really hit the reusing code path now. > > Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> > --- > mm/z3fold.c | 23 +---------------------- > 1 file changed, 1 insertion(+), 22 deletions(-) > > diff --git a/mm/z3fold.c b/mm/z3fold.c > index 5d8c21f2bc59..4e6814c5694f 100644 > --- a/mm/z3fold.c > +++ b/mm/z3fold.c > @@ -1102,28 +1102,7 @@ static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp, > bud = FIRST; > } > > - page = NULL; > - if (can_sleep) { > - spin_lock(&pool->stale_lock); > - zhdr = list_first_entry_or_null(&pool->stale, > - struct z3fold_header, buddy); > - /* > - * Before allocating a page, let's see if we can take one from > - * the stale pages list. cancel_work_sync() can sleep so we > - * limit this case to the contexts where we can sleep > - */ > - if (zhdr) { > - list_del(&zhdr->buddy); > - spin_unlock(&pool->stale_lock); > - cancel_work_sync(&zhdr->work); > - page = virt_to_page(zhdr); > - } else { > - spin_unlock(&pool->stale_lock); > - } > - } > - if (!page) > - page = alloc_page(gfp); > - > + page = alloc_page(gfp); > if (!page) > return -ENOMEM; Reviewed-by: Vitaly Wool <vitaly.wool@konsulko.com> > -- > 2.23.0 >
diff --git a/mm/z3fold.c b/mm/z3fold.c index 5d8c21f2bc59..4e6814c5694f 100644 --- a/mm/z3fold.c +++ b/mm/z3fold.c @@ -1102,28 +1102,7 @@ static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp, bud = FIRST; } - page = NULL; - if (can_sleep) { - spin_lock(&pool->stale_lock); - zhdr = list_first_entry_or_null(&pool->stale, - struct z3fold_header, buddy); - /* - * Before allocating a page, let's see if we can take one from - * the stale pages list. cancel_work_sync() can sleep so we - * limit this case to the contexts where we can sleep - */ - if (zhdr) { - list_del(&zhdr->buddy); - spin_unlock(&pool->stale_lock); - cancel_work_sync(&zhdr->work); - page = virt_to_page(zhdr); - } else { - spin_unlock(&pool->stale_lock); - } - } - if (!page) - page = alloc_page(gfp); - + page = alloc_page(gfp); if (!page) return -ENOMEM;
Currently if z3fold couldn't find an unbuddied page it would first try to pull a page off the stale list. But this approach is problematic. If init z3fold page fails later, the page should be freed via free_z3fold_page to clean up the relevant resource instead of using __free_page directly. And if page is successfully reused, it will BUG_ON later in __SetPageMovable because it's already non-lru movable page, i.e. PAGE_MAPPING_MOVABLE is already set in page->mapping. In order to fix all of these issues, we can simply remove the buggy use of stale list for allocation because can_sleep should always be false and we never really hit the reusing code path now. Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> --- mm/z3fold.c | 23 +---------------------- 1 file changed, 1 insertion(+), 22 deletions(-)