Commit 350f6bbc authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

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: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarSuren 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: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 284e0592

MAINTAINERS

+0 −1
Original line number Diff line number Diff line
@@ -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

include/linux/net_mm.h

deleted100644 → 0
+0 −17
Original line number Diff line number Diff line 
/* 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 */

include/net/tcp.h

+0 −1
Original line number Diff line number Diff line
@@ -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;

mm/memory.c

+5 −5
Original line number Diff line number Diff line
@@ -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 @@ 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;



	if (!vma_start_read(vma))

		goto inval;

net/ipv4/tcp.c

+4 −7
Original line number Diff line number Diff line
@@ -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;

	}