mm: add FAULT_FLAG_VMA_LOCK flag

Add a new flag to distinguish page faults handled under protection of
per-vma lock.

[surenb@google.com: document FAULT_FLAG_VMA_LOCK flag]
Link: https://lkml.kernel.org/r/20230301022720.1380780-2-surenb@google.com
Link: https://lore.kernel.org/all/20230301113648.7c279865@canb.auug.org.au/
Link: https://lkml.kernel.org/r/20230227173632.3292573-26-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Laurent Dufour <laurent.dufour@fr.ibm.com>
Cc: Dan Carpenter <error27@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0619f9f..1876825 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -479,7 +479,8 @@ static inline bool fault_flag_allow_retry_first(enum fault_flag flags)
        { FAULT_FLAG_USER,              "USER" }, \
        { FAULT_FLAG_REMOTE,            "REMOTE" }, \
        { FAULT_FLAG_INSTRUCTION,       "INSTRUCTION" }, \
-       { FAULT_FLAG_INTERRUPTIBLE,     "INTERRUPTIBLE" }
+       { FAULT_FLAG_INTERRUPTIBLE,     "INTERRUPTIBLE" }, \
+       { FAULT_FLAG_VMA_LOCK,          "VMA_LOCK" }
 
 /*
  * vm_fault is filled by the pagefault handler and passed to the vma's

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 3248ae4..3a6cf4c 100644 (file)
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -1049,6 +1049,7 @@ typedef struct {
  *                      mapped after the fault.
  * @FAULT_FLAG_ORIG_PTE_VALID: whether the fault has vmf->orig_pte cached.
  *                        We should only access orig_pte if this flag set.
+ * @FAULT_FLAG_VMA_LOCK: The fault is handled under VMA lock.
  *
  * About @FAULT_FLAG_ALLOW_RETRY and @FAULT_FLAG_TRIED: we can specify
  * whether we would allow page faults to retry by specifying these two
@@ -1086,6 +1087,7 @@ enum fault_flag {
        FAULT_FLAG_INTERRUPTIBLE =      1 << 9,
        FAULT_FLAG_UNSHARE =            1 << 10,
        FAULT_FLAG_ORIG_PTE_VALID =     1 << 11,
+       FAULT_FLAG_VMA_LOCK =           1 << 12,
 };
 
 typedef unsigned int __bitwise zap_flags_t;