Author: alc Date: Wed Dec 5 18:26:40 2018 New Revision: 341602 URL: https://svnweb.freebsd.org/changeset/base/341602
Log: Terminate a blist_alloc search when a blst_meta_alloc call fails with cursor == 0. Every call to blst_meta_alloc but the one at the root is made only when the meta-node is known to include a free block, so that either the allocation will succeed, the node hint will be updated, or the last block of the meta- node range is, and remains, free. But the call at the root is made without checking that there is a free block, so in the case that every block is allocated, there is no hint update to prevent the current code from looping forever. Submitted by: Doug Moore <do...@rice.edu> Reported by: pho Reviewed by: pho Tested by: pho X-MFC with: r340402 Differential Revision: https://reviews.freebsd.org/D17999 Modified: head/sys/kern/subr_blist.c Modified: head/sys/kern/subr_blist.c ============================================================================== --- head/sys/kern/subr_blist.c Wed Dec 5 18:19:29 2018 (r341601) +++ head/sys/kern/subr_blist.c Wed Dec 5 18:26:40 2018 (r341602) @@ -295,9 +295,9 @@ blist_alloc(blist_t bl, daddr_t count) * This loop iterates at most twice. An allocation failure in the * first iteration leads to a second iteration only if the cursor was * non-zero. When the cursor is zero, an allocation failure will - * reduce the hint, stopping further iterations. + * stop further iterations. */ - while (count <= bl->bl_root->bm_bighint) { + for (;;) { blk = blst_meta_alloc(bl->bl_root, bl->bl_cursor, count, bl->bl_radix); if (blk != SWAPBLK_NONE) { @@ -306,10 +306,10 @@ blist_alloc(blist_t bl, daddr_t count) if (bl->bl_cursor == bl->bl_blocks) bl->bl_cursor = 0; return (blk); - } + } else if (bl->bl_cursor == 0) + return (SWAPBLK_NONE); bl->bl_cursor = 0; } - return (SWAPBLK_NONE); } /* _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
