| Message ID | 20220605035557.3957759-2-chenwandun@huawei.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | a few cleanup and bugfixes about shmem | expand |
On Sun, Jun 05, 2022 at 11:55:55AM +0800, Chen Wandun wrote: > It will result in null pointer access if shmem_init_inodecache fail, > so check return value of shmem_init_inodecache You ignored my suggestion from v1. Here, let me write it out for you. +static int shmem_init_inodecache(void) { shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", sizeof(struct shmem_inode_info), 0, SLAB_PANIC|SLAB_ACCOUNT, shmem_init_inode); + if (!shmem_inode_cachep) + return -ENOMEM; + return 0; } ... + error = shmem_init_inodecache(); + if (error) + goto out2;
On 2022/6/5 19:49, Matthew Wilcox wrote: > On Sun, Jun 05, 2022 at 11:55:55AM +0800, Chen Wandun wrote: >> It will result in null pointer access if shmem_init_inodecache fail, >> so check return value of shmem_init_inodecache > You ignored my suggestion from v1. Here, let me write it out for you. Hi Matthew, I didn't ignore your suggestion, some explanation is needed, sorry for that. In V1, Kefeng point: "kmem_cache_create return a pointer to the cache on success, NULL on failure, so error = -ENOMEM; is right :)" so, I look some similar code such as init_inodecache in kinds of file system, they all return -ENOMEM on failure, so is it OK to return -ENOMEM on failure :) Besides, kmem_cache_create return NULL on failure, maybe returning error code on failure is more proper, but it is another job. > > +static int shmem_init_inodecache(void) > { > shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", > sizeof(struct shmem_inode_info), > 0, SLAB_PANIC|SLAB_ACCOUNT, shmem_init_inode); > + if (!shmem_inode_cachep) > + return -ENOMEM; > + return 0; > } > > ... > > + error = shmem_init_inodecache(); > + if (error) > + goto out2; > > > .
On Mon, Jun 06, 2022 at 09:34:13AM +0800, Chen Wandun wrote: > On 2022/6/5 19:49, Matthew Wilcox wrote: > > On Sun, Jun 05, 2022 at 11:55:55AM +0800, Chen Wandun wrote: > > > It will result in null pointer access if shmem_init_inodecache fail, > > > so check return value of shmem_init_inodecache > > You ignored my suggestion from v1. Here, let me write it out for you. > Hi Matthew, > I didn't ignore your suggestion, some explanation is needed, sorry for > that. > > In V1, Kefeng point: > "kmem_cache_create return a pointer to the cache on success, NULL on > failure, > so error = -ENOMEM; is right :)" > > so, I look some similar code such as init_inodecache in kinds of file > system, they all > return -ENOMEM on failure, so is it OK to return -ENOMEM on failure :) > > Besides, kmem_cache_create return NULL on failure, maybe returning error > code > on failure is more proper, but it is another job. I literally wrote out what I think you should do instead. Stop arguing. > > +static int shmem_init_inodecache(void) > > { > > shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", > > sizeof(struct shmem_inode_info), > > 0, SLAB_PANIC|SLAB_ACCOUNT, shmem_init_inode); > > + if (!shmem_inode_cachep) > > + return -ENOMEM; > > + return 0; > > } > > > > ... > > > > + error = shmem_init_inodecache(); > > + if (error) > > + goto out2; > > > > > > . >
在 2022/6/6 10:08, Matthew Wilcox 写道: > On Mon, Jun 06, 2022 at 09:34:13AM +0800, Chen Wandun wrote: >> On 2022/6/5 19:49, Matthew Wilcox wrote: >>> On Sun, Jun 05, 2022 at 11:55:55AM +0800, Chen Wandun wrote: >>>> It will result in null pointer access if shmem_init_inodecache fail, >>>> so check return value of shmem_init_inodecache >>> You ignored my suggestion from v1. Here, let me write it out for you. >> Hi Matthew, >> I didn't ignore your suggestion, some explanation is needed, sorry for >> that. >> >> In V1, Kefeng point: >> "kmem_cache_create return a pointer to the cache on success, NULL on >> failure, >> so error = -ENOMEM; is right :)" >> >> so, I look some similar code such as init_inodecache in kinds of file >> system, they all >> return -ENOMEM on failure, so is it OK to return -ENOMEM on failure :) >> >> Besides, kmem_cache_create return NULL on failure, maybe returning error >> code >> on failure is more proper, but it is another job. > I literally wrote out what I think you should do instead. Stop arguing. > >>> +static int shmem_init_inodecache(void) >>> { >>> shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", >>> sizeof(struct shmem_inode_info), >>> 0, SLAB_PANIC|SLAB_ACCOUNT, shmem_init_inode); >>> + if (!shmem_inode_cachep) >>> + return -ENOMEM; >>> + return 0; >>> } >>> >>> ... >>> >>> + error = shmem_init_inodecache(); >>> + if (error) >>> + goto out2; Oh, I misunderstood what you said, feel so sorry. I will send a new version. Thanks. >>> >>> >>> . > .
diff --git a/mm/shmem.c b/mm/shmem.c index 12d45a03f7fc..17f8297ece29 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -3775,11 +3775,13 @@ static void shmem_init_inode(void *foo) inode_init_once(&info->vfs_inode); } -static void shmem_init_inodecache(void) +static struct kmem_cache *shmem_init_inodecache(void) { shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", sizeof(struct shmem_inode_info), 0, SLAB_PANIC|SLAB_ACCOUNT, shmem_init_inode); + + return shmem_inode_cachep; } static void shmem_destroy_inodecache(void) @@ -3923,7 +3925,10 @@ void __init shmem_init(void) { int error; - shmem_init_inodecache(); + if (!shmem_init_inodecache()) { + error = -ENOMEM; + goto out2; + } error = register_filesystem(&shmem_fs_type); if (error) {
It will result in null pointer access if shmem_init_inodecache fail, so check return value of shmem_init_inodecache Signed-off-by: Chen Wandun <chenwandun@huawei.com> --- mm/shmem.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)