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BACKPORT: FROMGIT: mm: drop per-VMA lock when returning VM_FAULT_RETRY or VM_FAULT_COMPLETED

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handle_mm_fault returning VM_FAULT_RETRY or VM_FAULT_COMPLETED means
mmap_lock has been released.  However with per-VMA locks behavior is
different and the caller should still release it.  To make the rules
consistent for the caller, drop the per-VMA lock when returning
VM_FAULT_RETRY or VM_FAULT_COMPLETED.  Currently the only path returning
VM_FAULT_RETRY under per-VMA locks is do_swap_page and no path returns
VM_FAULT_COMPLETED for now.

Link: https://lkml.kernel.org/r/20230630211957.1341547-4-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Hillf Danton <hdanton@sina.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Laurent Dufour <ldufour@linux.ibm.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michel Lespinasse <michel@lespinasse.org>
Cc: Minchan Kim <minchan@google.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Punit Agrawal <punit.agrawal@bytedance.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

(cherry picked from commit 5197d920745dd42eae023986dbf053107ac238db
https: //git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-unstable)
[surenb: add the code from missing sanitize_fault_flags directly into
handle_mm_fault, add the fix for riscv]
Bug: 161210518
Change-Id: Iefd4e49bda940c457a70ecf40d074ad532959759
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
This commit is contained in:
Suren Baghdasaryan 2023-06-30 14:19:54 -07:00
parent 939d4b1ccc
commit 693d905ec0
6 changed files with 22 additions and 5 deletions
Download patch file Download diff file Expand all files Collapse all files

3
arch/arm64/mm/fault.c
View file

@ -612,7 +612,8 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,
goto lock_mmap;
}
fault = handle_mm_fault(vma, addr, mm_flags | FAULT_FLAG_VMA_LOCK, regs);
vma_end_read(vma);
if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED)))
vma_end_read(vma);
if (!(fault & VM_FAULT_RETRY)) {
count_vm_vma_lock_event(VMA_LOCK_SUCCESS);

3
arch/powerpc/mm/fault.c
View file

@ -489,7 +489,8 @@ static int ___do_page_fault(struct pt_regs *regs, unsigned long address,
}
fault = handle_mm_fault(vma, address, flags | FAULT_FLAG_VMA_LOCK, regs);
vma_end_read(vma);
if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED)))
vma_end_read(vma);
if (!(fault & VM_FAULT_RETRY)) {
count_vm_vma_lock_event(VMA_LOCK_SUCCESS);

3
arch/riscv/mm/fault.c
View file

@ -303,7 +303,8 @@ asmlinkage void do_page_fault(struct pt_regs *regs)
}
fault = handle_mm_fault(vma, addr, flags | FAULT_FLAG_VMA_LOCK, regs);
vma_end_read(vma);
if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED)))
vma_end_read(vma);
if (!(fault & VM_FAULT_RETRY)) {
count_vm_vma_lock_event(VMA_LOCK_SUCCESS);

3
arch/s390/mm/fault.c
View file

@ -414,7 +414,8 @@ static inline vm_fault_t do_exception(struct pt_regs *regs, int access)
goto lock_mmap;
}
fault = handle_mm_fault(vma, address, flags | FAULT_FLAG_VMA_LOCK, regs);
vma_end_read(vma);
if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED)))
vma_end_read(vma);
if (!(fault & VM_FAULT_RETRY)) {
count_vm_vma_lock_event(VMA_LOCK_SUCCESS);
goto out;

3
arch/x86/mm/fault.c
View file

@ -1362,7 +1362,8 @@ void do_user_addr_fault(struct pt_regs *regs,
goto lock_mmap;
}
fault = handle_mm_fault(vma, address, flags | FAULT_FLAG_VMA_LOCK, regs);
vma_end_read(vma);
if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED)))
vma_end_read(vma);
if (!(fault & VM_FAULT_RETRY)) {
count_vm_vma_lock_event(VMA_LOCK_SUCCESS);

12
mm/memory.c
View file

@ -3771,6 +3771,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
ret = VM_FAULT_RETRY;
vma_end_read(vma);
goto out;
}
@ -5243,6 +5244,17 @@ vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
__set_current_state(TASK_RUNNING);
#ifdef CONFIG_PER_VMA_LOCK
/*
* Per-VMA locks can't be used with FAULT_FLAG_RETRY_NOWAIT because of
* the assumption that lock is dropped on VM_FAULT_RETRY.
*/
if (WARN_ON_ONCE((flags &
(FAULT_FLAG_VMA_LOCK | FAULT_FLAG_RETRY_NOWAIT)) ==
(FAULT_FLAG_VMA_LOCK | FAULT_FLAG_RETRY_NOWAIT)))
return VM_FAULT_SIGSEGV;
#endif
/* do counter updates before entering really critical section. */
check_sync_rss_stat(current);