05ea88608d4e13 ("mm, hugetlbfs: introduce ->pagesize() to vm_operations_struct") adds a new ->pagesize() function to hugetlb_vm_ops, intended to cover all hugetlbfs backed files.
With System V shared memory model, if "huge page" is specified, the "shared memory" is backed by hugetlbfs files, but the mappings initiated via shmget/shmat have their original vm_ops overwritten with shm_vm_ops, so we need to add a ->pagesize function to shm_vm_ops. Otherwise, vma_kernel_pagesize() returns PAGE_SIZE given a hugetlbfs backed vma, result in below BUG:
fs/hugetlbfs/inode.c 443 if (unlikely(page_mapped(page))) { 444 BUG_ON(truncate_op);
[ 242.268342] hugetlbfs: oracle (4592): Using mlock ulimits for SHM_HUGETLB is deprecated [ 282.653208] ------------[ cut here ]------------ [ 282.708447] kernel BUG at fs/hugetlbfs/inode.c:444! [ 282.818957] Modules linked in: nfsv3 rpcsec_gss_krb5 nfsv4 ... [ 284.025873] CPU: 35 PID: 5583 Comm: oracle_5583_sbt Not tainted 4.14.35-1829.el7uek.x86_64 #2 [ 284.246609] task: ffff9bf0507aaf80 task.stack: ffffa9e625628000 [ 284.317455] RIP: 0010:remove_inode_hugepages+0x3db/0x3e2 .... [ 285.292389] Call Trace: [ 285.321630] hugetlbfs_evict_inode+0x1e/0x3e [ 285.372707] evict+0xdb/0x1af [ 285.408185] iput+0x1a2/0x1f7 [ 285.443661] dentry_unlink_inode+0xc6/0xf0 [ 285.492661] __dentry_kill+0xd8/0x18d [ 285.536459] dput+0x1b5/0x1ed [ 285.571939] __fput+0x18b/0x216 [ 285.609495] ____fput+0xe/0x10 [ 285.646030] task_work_run+0x90/0xa7 [ 285.688788] exit_to_usermode_loop+0xdd/0x116 [ 285.740905] do_syscall_64+0x187/0x1ae [ 285.785740] entry_SYSCALL_64_after_hwframe+0x150/0x0
Link: http://lkml.kernel.org/r/20180727211727.5020-1-jane.chu@oracle.com Fixes: 05ea88608d4e13 ("mm, hugetlbfs: introduce ->pagesize() to vm_operations_struct") Signed-off-by: Jane Chu jane.chu@oracle.com Suggested-by: Mike Kravetz mike.kravetz@oracle.com Reviewed-by: Mike Kravetz mike.kravetz@oracle.com Acked-by: Michal Hocko mhocko@suse.com Acked-by: Davidlohr Bueso dbueso@suse.de Cc: Dan Williams dan.j.williams@intel.com Cc: Michal Hocko mhocko@suse.com Cc: Jan Kara jack@suse.cz Cc: Jérôme Glisse jglisse@redhat.com Cc: Davidlohr Bueso dave@stgolabs.net Cc: Manfred Spraul manfred@colorfullife.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org --- --- ipc/shm.c | 12 ++++++++++++ mm/hugetlb.c | 7 +++++++ 2 files changed, 19 insertions(+)
diff --git a/ipc/shm.c b/ipc/shm.c index 051a3e1fb8df..fefa00d310fb 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -427,6 +427,17 @@ static int shm_split(struct vm_area_struct *vma, unsigned long addr) return 0; }
+static unsigned long shm_pagesize(struct vm_area_struct *vma) +{ + struct file *file = vma->vm_file; + struct shm_file_data *sfd = shm_file_data(file); + + if (sfd->vm_ops->pagesize) + return sfd->vm_ops->pagesize(vma); + + return PAGE_SIZE; +} + #ifdef CONFIG_NUMA static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new) { @@ -554,6 +565,7 @@ static const struct vm_operations_struct shm_vm_ops = { .close = shm_close, /* callback for when the vm-area is released */ .fault = shm_fault, .split = shm_split, + .pagesize = shm_pagesize, #if defined(CONFIG_NUMA) .set_policy = shm_set_policy, .get_policy = shm_get_policy, diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 039ddbc574e9..3103099f64fd 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -3167,6 +3167,13 @@ static vm_fault_t hugetlb_vm_op_fault(struct vm_fault *vmf) return 0; }
+/* + * When a new function is introduced to vm_operations_struct and added + * to hugetlb_vm_ops, please consider adding the function to shm_vm_ops. + * This is because under System V memory model, mappings created via + * shmget/shmat with "huge page" specified are backed by hugetlbfs files, + * their original vm_ops are overwritten with shm_vm_ops. + */ const struct vm_operations_struct hugetlb_vm_ops = { .fault = hugetlb_vm_op_fault, .open = hugetlb_vm_op_open,