Author: dougm Date: Thu Jul 11 20:52:39 2019 New Revision: 349923 URL: https://svnweb.freebsd.org/changeset/base/349923
Log: Address problems in blist_alloc introduced in r349777. The swap block allocator could become corrupted if a retry to allocate swap space, after a larger allocation attempt failed, allocated a smaller set of free blocks that ended on a 32- or 64-block boundary. Add tests to detect this kind of failure-to-extend-at-boundary and prevent the associated accounting screwup. Reported by: pho Tested by: pho Reviewed by: alc Approved by: markj (mentor) Discussed with: kib Differential Revision: https://reviews.freebsd.org/D20893 Modified: head/sys/kern/subr_blist.c Modified: head/sys/kern/subr_blist.c ============================================================================== --- head/sys/kern/subr_blist.c Thu Jul 11 20:29:50 2019 (r349922) +++ head/sys/kern/subr_blist.c Thu Jul 11 20:52:39 2019 (r349923) @@ -639,15 +639,27 @@ blst_next_leaf_alloc(blmeta_t *scan, daddr_t start, in * bitpos() returns zero here. */ avail = blk - start + bitpos(~scan->bm_bitmap); - if (avail < count) { + if (avail < count || avail == 0) { /* * There isn't a next leaf with enough free - * blocks at its beginning to complete the - * spanning allocation. + * blocks at its beginning to bother + * allocating. */ return (avail); } maxcount = imin(avail, maxcount); + if (maxcount % BLIST_BMAP_RADIX == 0) { + /* + * There was no next leaf. Back scan up to + * last leaf. + */ + --scan; + while (radix != BLIST_BMAP_RADIX) { + radix /= BLIST_META_RADIX; + --scan; + } + blk -= BLIST_BMAP_RADIX; + } } } _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
