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

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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>

(cherry picked from commit 698dcd77360a3ce15dfc6fe55f9b5572ad4c4291
https: //git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-unstable)
[surenb: skip tcp-related changes]

Bug: 293665307
Change-Id: I73d9d1e4f96419d4723a920fc5960e806749c368
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
This commit is contained in:
Matthew Wilcox (Oracle) 2023-07-24 19:54:02 +01:00 committed by Suren Baghdasaryan
parent 4cb518a06f
commit e26044769f
1 changed files with 5 additions and 4 deletions
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9
mm/memory.c
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@ -5267,6 +5267,11 @@ 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.
@ -5438,10 +5443,6 @@ struct vm_area_struct *lock_vma_under_rcu(struct mm_struct *mm,
if (!vma)
goto inval;
/* Only anonymous vmas are supported for now */
if (!vma_is_anonymous(vma))
goto inval;
if (!vma_start_read(vma))
goto inval;