Page MenuHomeFreeBSD

swap_pager: Handle large swap_pager_reserve() requests
ClosedPublic

Authored by markj on Sep 7 2021, 3:46 PM.
Tags
None
Referenced Files
Unknown Object (File)
Thu, Oct 16, 4:11 PM
Unknown Object (File)
Sep 17 2025, 10:13 AM
Unknown Object (File)
Sep 16 2025, 10:30 AM
Unknown Object (File)
Sep 11 2025, 7:35 AM
Unknown Object (File)
Sep 5 2025, 10:58 AM
Unknown Object (File)
Sep 5 2025, 9:03 AM
Unknown Object (File)
Aug 30 2025, 12:41 PM
Unknown Object (File)
Aug 28 2025, 12:03 AM
Subscribers

Details

Summary

This interface is used solely by md(4) when the MD_RESERVE flag is
specified, as in mdconfig -a -t swap -s 1G -o reserve. It
pre-allocates swap blocks for the entire object.

The number of blocks to be reserved is specified as a vm_size_t, but
swp_pager_getswapspace() can allocate at most INT_MAX blocks. vm_size_t
also seems like the incorrect type to use here it refers only to the
size of the VM object, not the size of a mapping. So:

  • change the type of "size" in swap_pager_reserve() to vm_pindex_t, and
  • clamp the requested number of blocks for a single swp_pager_getswapspace() call to INT_MAX.

Reported by: syzkaller

Diff Detail

Repository
rG FreeBSD src repository
Lint
Lint Not Applicable
Unit
Tests Not Applicable