Author: alc Date: Thu Dec 1 17:26:37 2016 New Revision: 309365 URL: https://svnweb.freebsd.org/changeset/base/309365
Log: During vm_page_cache()'s call to vm_radix_insert(), if vm_page_alloc() was called to allocate a new page of radix trie nodes, there could be a call to vm_radix_remove() on the same trie (of PG_CACHED pages) as the in-progress vm_radix_insert(). With the removal of PG_CACHED pages, we can simplify vm_radix_insert() and vm_radix_remove() by removing the flags on the root of the trie that were used to detect this case and the code for restarting vm_radix_insert() when it happened. Reviewed by: kib, markj Tested by: pho Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D8664 Modified: head/sys/vm/_vm_radix.h head/sys/vm/vm_object.c head/sys/vm/vm_radix.c Modified: head/sys/vm/_vm_radix.h ============================================================================== --- head/sys/vm/_vm_radix.h Thu Dec 1 16:54:02 2016 (r309364) +++ head/sys/vm/_vm_radix.h Thu Dec 1 17:26:37 2016 (r309365) @@ -36,12 +36,8 @@ */ struct vm_radix { uintptr_t rt_root; - uint8_t rt_flags; }; -#define RT_INSERT_INPROG 0x01 -#define RT_TRIE_MODIFIED 0x02 - #ifdef _KERNEL static __inline boolean_t Modified: head/sys/vm/vm_object.c ============================================================================== --- head/sys/vm/vm_object.c Thu Dec 1 16:54:02 2016 (r309364) +++ head/sys/vm/vm_object.c Thu Dec 1 17:26:37 2016 (r309365) @@ -205,7 +205,6 @@ vm_object_zinit(void *mem, int size, int object->type = OBJT_DEAD; object->ref_count = 0; object->rtree.rt_root = 0; - object->rtree.rt_flags = 0; object->paging_in_progress = 0; object->resident_page_count = 0; object->shadow_count = 0; Modified: head/sys/vm/vm_radix.c ============================================================================== --- head/sys/vm/vm_radix.c Thu Dec 1 16:54:02 2016 (r309364) +++ head/sys/vm/vm_radix.c Thu Dec 1 17:26:37 2016 (r309365) @@ -341,8 +341,6 @@ vm_radix_insert(struct vm_radix *rtree, index = page->pindex; -restart: - /* * The owner of record for root is not really important because it * will never be used. @@ -360,32 +358,10 @@ restart: panic("%s: key %jx is already present", __func__, (uintmax_t)index); clev = vm_radix_keydiff(m->pindex, index); - - /* - * During node allocation the trie that is being - * walked can be modified because of recursing radix - * trie operations. - * If this is the case, the recursing functions signal - * such situation and the insert operation must - * start from scratch again. - * The freed radix node will then be in the UMA - * caches very likely to avoid the same situation - * to happen. - */ - rtree->rt_flags |= RT_INSERT_INPROG; tmp = vm_radix_node_get(vm_radix_trimkey(index, clev + 1), 2, clev); - rtree->rt_flags &= ~RT_INSERT_INPROG; - if (tmp == NULL) { - rtree->rt_flags &= ~RT_TRIE_MODIFIED; + if (tmp == NULL) return (ENOMEM); - } - if ((rtree->rt_flags & RT_TRIE_MODIFIED) != 0) { - rtree->rt_flags &= ~RT_TRIE_MODIFIED; - tmp->rn_count = 0; - vm_radix_node_put(tmp); - goto restart; - } *parentp = tmp; vm_radix_addpage(tmp, index, clev, page); vm_radix_addpage(tmp, m->pindex, clev, m); @@ -409,21 +385,9 @@ restart: */ newind = rnode->rn_owner; clev = vm_radix_keydiff(newind, index); - - /* See the comments above. */ - rtree->rt_flags |= RT_INSERT_INPROG; tmp = vm_radix_node_get(vm_radix_trimkey(index, clev + 1), 2, clev); - rtree->rt_flags &= ~RT_INSERT_INPROG; - if (tmp == NULL) { - rtree->rt_flags &= ~RT_TRIE_MODIFIED; + if (tmp == NULL) return (ENOMEM); - } - if ((rtree->rt_flags & RT_TRIE_MODIFIED) != 0) { - rtree->rt_flags &= ~RT_TRIE_MODIFIED; - tmp->rn_count = 0; - vm_radix_node_put(tmp); - goto restart; - } *parentp = tmp; vm_radix_addpage(tmp, index, clev, page); slot = vm_radix_slot(newind, clev); @@ -708,20 +672,6 @@ vm_radix_remove(struct vm_radix *rtree, vm_page_t m; int i, slot; - /* - * Detect if a page is going to be removed from a trie which is - * already undergoing another trie operation. - * Right now this is only possible for vm_radix_remove() recursing - * into vm_radix_insert(). - * If this is the case, the caller must be notified about this - * situation. It will also takecare to update the RT_TRIE_MODIFIED - * accordingly. - * The RT_TRIE_MODIFIED bit is set here because the remove operation - * will always succeed. - */ - if ((rtree->rt_flags & RT_INSERT_INPROG) != 0) - rtree->rt_flags |= RT_TRIE_MODIFIED; - rnode = vm_radix_getroot(rtree); if (vm_radix_isleaf(rnode)) { m = vm_radix_topage(rnode); @@ -776,9 +726,6 @@ vm_radix_reclaim_allnodes(struct vm_radi { struct vm_radix_node *root; - KASSERT((rtree->rt_flags & RT_INSERT_INPROG) == 0, - ("vm_radix_reclaim_allnodes: unexpected trie recursion")); - root = vm_radix_getroot(rtree); if (root == NULL) return; _______________________________________________ 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"
