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mm: allow per-VMA locks on file-backed VMAs 

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.

Link: https://lkml.kernel.org/r/20230724185410.1124082-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Cc: Arjun Roy <arjunroy@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Punit Agrawal <punit.agrawal@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2023-07-24 19:54:02 +01:00 committed by Andrew Morton
parent 284e059204
commit 350f6bbca1
5 changed files with 9 additions and 31 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
MAINTAINERS
View File

@ -14829,7 +14829,6 @@ NETWORKING [TCP]
M: Eric Dumazet <edumazet@google.com>
L: netdev@vger.kernel.org
S: Maintained
F: include/linux/net_mm.h
F: include/linux/tcp.h
F: include/net/tcp.h
F: include/trace/events/tcp.h

17
include/linux/net_mm.h
View File

@ -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 */

1
include/net/tcp.h
View File

@ -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;

10
mm/memory.c
View File

@ -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>
@ -5223,6 +5222,11 @@ 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.
@ -5394,10 +5398,6 @@ retry:
if (!vma)
goto inval;
/* Only anonymous and tcp vmas are supported for now */
if (!vma_is_anonymous(vma) && !vma_is_tcp(vma))
goto inval;
if (!vma_start_read(vma))
goto inval;

11
net/ipv4/tcp.c
View File

@ -1739,7 +1739,7 @@ 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,
@ -2042,13 +2042,10 @@ 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;
}
@ -2058,7 +2055,7 @@ 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;
}