| Message ID | 42353193-6896-aa85-9127-78881d5fef66@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | tmpfs: HUGEPAGE and MEM_LOCK fcntls and memfds | expand |
On Fri, Jul 30, 2021 at 12:31 AM Hugh Dickins <hughd@google.com> wrote: > > There's a block of code in shmem_setattr() to add the inode to > shmem_unused_huge_shrink()'s shrinklist when lowering i_size: it dates > from before 5.7 changed truncation to do split_huge_page() for itself, > and should have been removed at that time. > > I am over-stating that: split_huge_page() can fail (notably if there's > an extra reference to the page at that time), so there might be value in > retrying. But there were already retries as truncation worked through > the tails, and this addition risks repeating unsuccessful retries > indefinitely: I'd rather remove it now, and work on reducing the > chance of split_huge_page() failures separately, if we need to. Yes, agreed. Reviewed-by: Yang Shi <shy828301@gmail.com> > > Fixes: 71725ed10c40 ("mm: huge tmpfs: try to split_huge_page() when punching hole") > Signed-off-by: Hugh Dickins <hughd@google.com> > --- > mm/shmem.c | 19 ------------------- > 1 file changed, 19 deletions(-) > > diff --git a/mm/shmem.c b/mm/shmem.c > index 24c9da6b41c2..ce3ccaac54d6 100644 > --- a/mm/shmem.c > +++ b/mm/shmem.c > @@ -1061,7 +1061,6 @@ static int shmem_setattr(struct user_namespace *mnt_userns, > { > struct inode *inode = d_inode(dentry); > struct shmem_inode_info *info = SHMEM_I(inode); > - struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); > int error; > > error = setattr_prepare(&init_user_ns, dentry, attr); > @@ -1097,24 +1096,6 @@ static int shmem_setattr(struct user_namespace *mnt_userns, > if (oldsize > holebegin) > unmap_mapping_range(inode->i_mapping, > holebegin, 0, 1); > - > - /* > - * Part of the huge page can be beyond i_size: subject > - * to shrink under memory pressure. > - */ > - if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) { > - spin_lock(&sbinfo->shrinklist_lock); > - /* > - * _careful to defend against unlocked access to > - * ->shrink_list in shmem_unused_huge_shrink() > - */ > - if (list_empty_careful(&info->shrinklist)) { > - list_add_tail(&info->shrinklist, > - &sbinfo->shrinklist); > - sbinfo->shrinklist_len++; > - } > - spin_unlock(&sbinfo->shrinklist_lock); > - } > } > } > > -- > 2.26.2 >
diff --git a/mm/shmem.c b/mm/shmem.c index 24c9da6b41c2..ce3ccaac54d6 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1061,7 +1061,6 @@ static int shmem_setattr(struct user_namespace *mnt_userns, { struct inode *inode = d_inode(dentry); struct shmem_inode_info *info = SHMEM_I(inode); - struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); int error; error = setattr_prepare(&init_user_ns, dentry, attr); @@ -1097,24 +1096,6 @@ static int shmem_setattr(struct user_namespace *mnt_userns, if (oldsize > holebegin) unmap_mapping_range(inode->i_mapping, holebegin, 0, 1); - - /* - * Part of the huge page can be beyond i_size: subject - * to shrink under memory pressure. - */ - if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) { - spin_lock(&sbinfo->shrinklist_lock); - /* - * _careful to defend against unlocked access to - * ->shrink_list in shmem_unused_huge_shrink() - */ - if (list_empty_careful(&info->shrinklist)) { - list_add_tail(&info->shrinklist, - &sbinfo->shrinklist); - sbinfo->shrinklist_len++; - } - spin_unlock(&sbinfo->shrinklist_lock); - } } }
There's a block of code in shmem_setattr() to add the inode to shmem_unused_huge_shrink()'s shrinklist when lowering i_size: it dates from before 5.7 changed truncation to do split_huge_page() for itself, and should have been removed at that time. I am over-stating that: split_huge_page() can fail (notably if there's an extra reference to the page at that time), so there might be value in retrying. But there were already retries as truncation worked through the tails, and this addition risks repeating unsuccessful retries indefinitely: I'd rather remove it now, and work on reducing the chance of split_huge_page() failures separately, if we need to. Fixes: 71725ed10c40 ("mm: huge tmpfs: try to split_huge_page() when punching hole") Signed-off-by: Hugh Dickins <hughd@google.com> --- mm/shmem.c | 19 ------------------- 1 file changed, 19 deletions(-)