x86/unwind/orc: Fix unwind_get_return_address_ptr() for inactive tasks

[linux-2.6-microblaze.git] / mm / madvise.c

diff --git a/mm/madvise.c b/mm/madvise.c
index 4bb30ed..8cbd8c1 100644 (file)
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -27,6 +27,7 @@
 #include <linux/swapops.h>
 #include <linux/shmem_fs.h>
 #include <linux/mmu_notifier.h>
+#include <linux/sched/mm.h>
 
 #include <asm/tlb.h>
 
@@ -1090,6 +1091,23 @@ int do_madvise(unsigned long start, size_t len_in, int behavior)
        if (write) {
                if (down_write_killable(&current->mm->mmap_sem))
                        return -EINTR;
+
+               /*
+                * We may have stolen the mm from another process
+                * that is undergoing core dumping.
+                *
+                * Right now that's io_ring, in the future it may
+                * be remote process management and not "current"
+                * at all.
+                *
+                * We need to fix core dumping to not do this,
+                * but for now we have the mmget_still_valid()
+                * model.
+                */
+               if (!mmget_still_valid(current->mm)) {
+                       up_write(&current->mm->mmap_sem);
+                       return -EINTR;
+               }
        } else {
                down_read(&current->mm->mmap_sem);
        }