Commit 4089eef0 authored Jun 30, 2023 by Suren Baghdasaryan Committed by Andrew Morton Aug 24, 2023

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

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.

[willy@infradead.org: fix riscv]
  Link: https://lkml.kernel.org/r/CAJuCfpE6GWEx1rPBmNpUfoD5o-gNFz9-UFywzCE2PbEGBiVz7g@mail.gmail.com
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>
Tested-by: Conor Dooley <conor.dooley@microchip.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>

parent 7a32b58b

arch/arm64/mm/fault.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -599,6 +599,7 @@ 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);
		if (!(fault & (VM_FAULT_RETRY \| VM_FAULT_COMPLETED)))
		vma_end_read(vma);

		if (!(fault & VM_FAULT_RETRY)) {

arch/powerpc/mm/fault.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -488,6 +488,7 @@ static int ___do_page_fault(struct pt_regs *regs, unsigned long address,
		}

		fault = handle_mm_fault(vma, address, flags \| FAULT_FLAG_VMA_LOCK, regs);
		if (!(fault & (VM_FAULT_RETRY \| VM_FAULT_COMPLETED)))
		vma_end_read(vma);

		if (!(fault & VM_FAULT_RETRY)) {

arch/riscv/mm/fault.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -296,6 +296,7 @@ void handle_page_fault(struct pt_regs *regs)
		}

		fault = handle_mm_fault(vma, addr, flags \| FAULT_FLAG_VMA_LOCK, regs);
		if (!(fault & (VM_FAULT_RETRY \| VM_FAULT_COMPLETED)))
		vma_end_read(vma);

		if (!(fault & VM_FAULT_RETRY)) {

arch/s390/mm/fault.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -417,6 +417,7 @@ 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);
		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);

arch/x86/mm/fault.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -1340,6 +1340,7 @@ void do_user_addr_fault(struct pt_regs *regs,
		goto lock_mmap;
		}
		fault = handle_mm_fault(vma, address, flags \| FAULT_FLAG_VMA_LOCK, regs);
		if (!(fault & (VM_FAULT_RETRY \| VM_FAULT_COMPLETED)))
		vma_end_read(vma);

		if (!(fault & VM_FAULT_RETRY)) {