The patch titled
Subject: ipc/shm.c add ->pagesize function to shm_vm_ops
has been added to the -mm tree. Its filename is
ipc-shmc-add-pagesize-function-to-shm_vm_ops.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/ipc-shmc-add-pagesize-function-to-shm_vm_ops.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/ipc-shmc-add-pagesize-function-to-shm_vm_ops.patch
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------------------------------------------------------
From: Jane Chu <jane.chu@xxxxxxxxxx>
Subject: ipc/shm.c add ->pagesize function to shm_vm_ops
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@xxxxxxxxxx
Fixes: 05ea88608d4e13 ("mm, hugetlbfs: introduce ->pagesize() to vm_operations_struct")
Signed-off-by: Jane Chu <jane.chu@xxxxxxxxxx>
Suggested-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Jérôme Glisse <jglisse@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
diff -puN include/linux/mm.h~ipc-shmc-add-pagesize-function-to-shm_vm_ops include/linux/mm.h
--- a/include/linux/mm.h~ipc-shmc-add-pagesize-function-to-shm_vm_ops
+++ a/include/linux/mm.h
@@ -389,6 +389,13 @@ enum page_entry_size {
* These are the virtual MM functions - opening of an area, closing and
* unmapping it (needed to keep files on disk up-to-date etc), pointer
* to the functions called when a no-page or a wp-page exception occurs.
+ *
+ * Note, 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, though
+ * mappings created via shmget/shmat with "huge page" specified are
+ * backed by hugetlbfs files, their original vm_ops are overwritten with
+ * shm_vm_ops.
*/
struct vm_operations_struct {
void (*open)(struct vm_area_struct * area);
diff -puN ipc/shm.c~ipc-shmc-add-pagesize-function-to-shm_vm_ops ipc/shm.c
--- a/ipc/shm.c~ipc-shmc-add-pagesize-function-to-shm_vm_ops
+++ a/ipc/shm.c
@@ -427,6 +427,17 @@ static int shm_split(struct vm_area_stru
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
.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,
_
Patches currently in -mm which might be from jane.chu@xxxxxxxxxx are
ipc-shmc-add-pagesize-function-to-shm_vm_ops.patch
