Remove the TCP layering violation by allowing per-VMA locks on all VMAs.
The fault path will immediately fail in handle_mm_fault(). There may be
a small performance reduction from this patch as a little unnecessary work
will be done on each page fault. See later patches for the improvement.
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Reviewed-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: Arjun Roy <arjunroy@xxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
---
MAINTAINERS | 1 -
include/linux/net_mm.h | 17 -----------------
include/net/tcp.h | 1 -
mm/memory.c | 12 ++++++------
net/ipv4/tcp.c | 11 ++++-------
5 files changed, 10 insertions(+), 32 deletions(-)
delete mode 100644 include/linux/net_mm.h
diff --git a/MAINTAINERS b/MAINTAINERS
index 220566cd8da8..f5f5134219b4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -14874,7 +14874,6 @@ NETWORKING [TCP]
M: Eric Dumazet <edumazet@xxxxxxxxxx>
L: netdev@xxxxxxxxxxxxxxx
S: Maintained
-F: include/linux/net_mm.h
F: include/linux/tcp.h
F: include/net/tcp.h
F: include/trace/events/tcp.h
diff --git a/include/linux/net_mm.h b/include/linux/net_mm.h
deleted file mode 100644
index b298998bd5a0..000000000000
--- a/include/linux/net_mm.h
+++ /dev/null
@@ -1,17 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-or-later */
-#ifdef CONFIG_MMU
-
-#ifdef CONFIG_INET
-extern const struct vm_operations_struct tcp_vm_ops;
-static inline bool vma_is_tcp(const struct vm_area_struct *vma)
-{
- return vma->vm_ops == &tcp_vm_ops;
-}
-#else
-static inline bool vma_is_tcp(const struct vm_area_struct *vma)
-{
- return false;
-}
-#endif /* CONFIG_INET*/
-
-#endif /* CONFIG_MMU */
diff --git a/include/net/tcp.h b/include/net/tcp.h
index d17cb8ab4c48..9d1d312c90c2 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -45,7 +45,6 @@
#include <linux/memcontrol.h>
#include <linux/bpf-cgroup.h>
#include <linux/siphash.h>
-#include <linux/net_mm.h>
extern struct inet_hashinfo tcp_hashinfo;
diff --git a/mm/memory.c b/mm/memory.c
index 7ff73a197cce..c7ad754dd8ed 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -77,7 +77,6 @@
#include <linux/ptrace.h>
#include <linux/vmalloc.h>
#include <linux/sched/sysctl.h>
-#include <linux/net_mm.h>
#include <trace/events/kmem.h>
@@ -5362,6 +5361,11 @@ vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
goto out;
}
+ if ((flags & FAULT_FLAG_VMA_LOCK) && !vma_is_anonymous(vma)) {
+ vma_end_read(vma);
+ return VM_FAULT_RETRY;
+ }
+
/*
* Enable the memcg OOM handling for faults triggered in user
* space. Kernel faults are handled more gracefully.
@@ -5533,12 +5537,8 @@ struct vm_area_struct *lock_vma_under_rcu(struct mm_struct *mm,
if (!vma)
goto inval;
- /* Only anonymous and tcp vmas are supported for now */
- if (!vma_is_anonymous(vma) && !vma_is_tcp(vma))
- goto inval;
-
/* find_mergeable_anon_vma uses adjacent vmas which are not locked */
- if (!vma->anon_vma && !vma_is_tcp(vma))
+ if (vma_is_anonymous(vma) && !vma->anon_vma)
goto inval;
if (!vma_start_read(vma))
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index aca5620cf3ba..f7391d017c4c 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1740,7 +1740,7 @@ void tcp_update_recv_tstamps(struct sk_buff *skb,
}
#ifdef CONFIG_MMU
-const struct vm_operations_struct tcp_vm_ops = {
+static const struct vm_operations_struct tcp_vm_ops = {
};
int tcp_mmap(struct file *file, struct socket *sock,
@@ -2043,13 +2043,10 @@ static struct vm_area_struct *find_tcp_vma(struct mm_struct *mm,
unsigned long address,
bool *mmap_locked)
{
- struct vm_area_struct *vma = NULL;
+ struct vm_area_struct *vma = lock_vma_under_rcu(mm, address);
-#ifdef CONFIG_PER_VMA_LOCK
- vma = lock_vma_under_rcu(mm, address);
-#endif
if (vma) {
- if (!vma_is_tcp(vma)) {
+ if (vma->vm_ops != &tcp_vm_ops) {
vma_end_read(vma);
return NULL;
}
@@ -2059,7 +2056,7 @@ static struct vm_area_struct *find_tcp_vma(struct mm_struct *mm,
mmap_read_lock(mm);
vma = vma_lookup(mm, address);
- if (!vma || !vma_is_tcp(vma)) {
+ if (!vma || vma->vm_ops != &tcp_vm_ops) {
mmap_read_unlock(mm);
return NULL;
}
--
2.39.2
