| Message ID | 20220429064051.61552-5-linmiaohe@huawei.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | A few fixup patches for z3fold | expand |
On Fri, Apr 29, 2022 at 8:40 AM Miaohe Lin <linmiaohe@huawei.com> wrote: > > If trylock_page fails, the page won't be non-lru movable page. When this > page is freed via free_z3fold_page, it will trigger bug on PageMovable > check in __ClearPageMovable. Throw warning on failure of trylock_page to > guard against such rare case just as what zsmalloc does. I don't see how this is better than what we currently have. We can check if a page is movable before calling __ClearPageMovable instead. ~Vitaly > Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> > --- > mm/z3fold.c | 7 +++---- > 1 file changed, 3 insertions(+), 4 deletions(-) > > diff --git a/mm/z3fold.c b/mm/z3fold.c > index 4e6814c5694f..b3b4e65c107f 100644 > --- a/mm/z3fold.c > +++ b/mm/z3fold.c > @@ -1122,10 +1122,9 @@ static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp, > __SetPageMovable(page, pool->inode->i_mapping); > unlock_page(page); > } else { > - if (trylock_page(page)) { > - __SetPageMovable(page, pool->inode->i_mapping); > - unlock_page(page); > - } > + WARN_ON(!trylock_page(page)); > + __SetPageMovable(page, pool->inode->i_mapping); > + unlock_page(page); > } > z3fold_page_lock(zhdr); > > -- > 2.23.0 >
On 2022/5/19 15:10, Vitaly Wool wrote: > On Fri, Apr 29, 2022 at 8:40 AM Miaohe Lin <linmiaohe@huawei.com> wrote: >> >> If trylock_page fails, the page won't be non-lru movable page. When this >> page is freed via free_z3fold_page, it will trigger bug on PageMovable >> check in __ClearPageMovable. Throw warning on failure of trylock_page to >> guard against such rare case just as what zsmalloc does. > > I don't see how this is better than what we currently have. We can > check if a page is movable before calling __ClearPageMovable instead. Currently the z3fold page (unless headless page) is assumed to be non-lru movable. We will always do __ClearPageMovable in free_z3fold_page which will trigger BUG_ON !PageMovable now. And do you mean we should do something like below ? diff --git a/mm/z3fold.c b/mm/z3fold.c index f41f8b0d9e9a..a244bb5dcb34 100644 --- a/mm/z3fold.c +++ b/mm/z3fold.c @@ -417,9 +417,10 @@ static struct z3fold_header *init_z3fold_page(struct page *page, bool headless, /* Resets the struct page fields and frees the page */ static void free_z3fold_page(struct page *page, bool headless) { - if (!headless) { + if (likely(__PageMovable(page))) { lock_page(page); - __ClearPageMovable(page); + if (PageMovable(page)) + __ClearPageMovable(page); unlock_page(page); } __free_page(page); Thanks! > > ~Vitaly > >> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> >> --- >> mm/z3fold.c | 7 +++---- >> 1 file changed, 3 insertions(+), 4 deletions(-) >> >> diff --git a/mm/z3fold.c b/mm/z3fold.c >> index 4e6814c5694f..b3b4e65c107f 100644 >> --- a/mm/z3fold.c >> +++ b/mm/z3fold.c >> @@ -1122,10 +1122,9 @@ static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp, >> __SetPageMovable(page, pool->inode->i_mapping); >> unlock_page(page); >> } else { >> - if (trylock_page(page)) { >> - __SetPageMovable(page, pool->inode->i_mapping); >> - unlock_page(page); >> - } >> + WARN_ON(!trylock_page(page)); >> + __SetPageMovable(page, pool->inode->i_mapping); >> + unlock_page(page); >> } >> z3fold_page_lock(zhdr); >> >> -- >> 2.23.0 >> > . >
diff --git a/mm/z3fold.c b/mm/z3fold.c index 4e6814c5694f..b3b4e65c107f 100644 --- a/mm/z3fold.c +++ b/mm/z3fold.c @@ -1122,10 +1122,9 @@ static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp, __SetPageMovable(page, pool->inode->i_mapping); unlock_page(page); } else { - if (trylock_page(page)) { - __SetPageMovable(page, pool->inode->i_mapping); - unlock_page(page); - } + WARN_ON(!trylock_page(page)); + __SetPageMovable(page, pool->inode->i_mapping); + unlock_page(page); } z3fold_page_lock(zhdr);
If trylock_page fails, the page won't be non-lru movable page. When this page is freed via free_z3fold_page, it will trigger bug on PageMovable check in __ClearPageMovable. Throw warning on failure of trylock_page to guard against such rare case just as what zsmalloc does. Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> --- mm/z3fold.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)