Author: alc Date: Sun Nov 27 01:42:53 2016 New Revision: 309203 URL: https://svnweb.freebsd.org/changeset/base/309203
Log: Recursion on the free page queue mutex occurred when UMA needed to allocate a new page of radix trie nodes to complete a vm_radix_insert() operation that was requested by vm_page_cache(). Specifically, vm_page_cache() already held the free page queue lock when UMA tried to acquire it through a call to vm_page_alloc(). This code path no longer exists, so there is no longer any reason to allow recursion on the free page queue mutex. Improve nearby comments. Reviewed by: kib, markj Tested by: pho Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D8628 Modified: head/sys/vm/vm_page.c Modified: head/sys/vm/vm_page.c ============================================================================== --- head/sys/vm/vm_page.c Sat Nov 26 23:22:32 2016 (r309202) +++ head/sys/vm/vm_page.c Sun Nov 27 01:42:53 2016 (r309203) @@ -1512,19 +1512,17 @@ vm_page_alloc(vm_object_t object, vm_pin } /* - * The page allocation request can came from consumers which already - * hold the free page queue mutex, like vm_page_insert() in - * vm_page_cache(). + * Allocate a page if the number of free pages exceeds the minimum + * for the request class. */ - mtx_lock_flags(&vm_page_queue_free_mtx, MTX_RECURSE); + mtx_lock(&vm_page_queue_free_mtx); if (vm_cnt.v_free_count > vm_cnt.v_free_reserved || (req_class == VM_ALLOC_SYSTEM && vm_cnt.v_free_count > vm_cnt.v_interrupt_free_min) || (req_class == VM_ALLOC_INTERRUPT && vm_cnt.v_free_count > 0)) { /* - * Allocate from the free queue if the number of free pages - * exceeds the minimum for the request class. + * Can we allocate the page from a reservation? */ #if VM_NRESERVLEVEL > 0 if (object == NULL || (object->flags & (OBJ_COLORED | @@ -1532,6 +1530,9 @@ vm_page_alloc(vm_object_t object, vm_pin vm_reserv_alloc_page(object, pindex, mpred)) == NULL) #endif { + /* + * If not, allocate it from the free page queues. + */ m = vm_phys_alloc_pages(object != NULL ? VM_FREEPOOL_DEFAULT : VM_FREEPOOL_DIRECT, 0); #if VM_NRESERVLEVEL > 0 @@ -1841,7 +1842,7 @@ vm_page_alloc_freelist(int flind, int re /* * Do not allocate reserved pages unless the req has asked for it. */ - mtx_lock_flags(&vm_page_queue_free_mtx, MTX_RECURSE); + mtx_lock(&vm_page_queue_free_mtx); if (vm_cnt.v_free_count > vm_cnt.v_free_reserved || (req_class == VM_ALLOC_SYSTEM && vm_cnt.v_free_count > vm_cnt.v_interrupt_free_min) || _______________________________________________ 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"
