From: NeilBrown neilb@suse.de

mainline inclusion from mainline-v5.15-rc1 commit e38b3f20059426a0adbde014ff71071739ab5226 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I7RRY4 CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

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alloc_pages_bulk_array() attempts to allocate at least one page based on the provided pages, and then opportunistically allocates more if that can be done without dropping the spinlock.

So if it returns fewer than requested, that could just mean that it needed to drop the lock. In that case, try again immediately.

Only pause for a time if no progress could be made.

Reported-and-tested-by: Mike Javorski mike.javorski@gmail.com Reported-and-tested-by: Lothar Paltins lopa@mailbox.org Fixes: f6e70aab9dfe ("SUNRPC: refresh rq_pages using a bulk page allocator") Signed-off-by: NeilBrown neilb@suse.de Acked-by: Mel Gorman mgorman@suse.com Signed-off-by: Chuck Lever chuck.lever@oracle.com Signed-off-by: ZhaoLong Wang wangzhaolong1@huawei.com

Conflicts: net/sunrpc/svc_xprt.c --- net/sunrpc/svc_xprt.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c index 362487f3a6de..f56b4df6ce28 100644 --- a/net/sunrpc/svc_xprt.c +++ b/net/sunrpc/svc_xprt.c @@ -643,7 +643,7 @@ static int svc_alloc_arg(struct svc_rqst *rqstp) { struct svc_serv *serv = rqstp->rq_server; struct xdr_buf *arg = &rqstp->rq_arg; - unsigned long pages, filled; + unsigned long pages, filled, ret;

pages = (serv->sv_max_mesg + 2 * PAGE_SIZE) >> PAGE_SHIFT; if (pages > RPCSVC_MAXPAGES) { @@ -653,11 +653,12 @@ static int svc_alloc_arg(struct svc_rqst *rqstp) pages = RPCSVC_MAXPAGES; }

- for (;;) { - filled = alloc_pages_bulk_array(GFP_KERNEL, pages, - rqstp->rq_pages); - if (filled == pages) - break; + for (filled = 0; filled < pages; filled = ret) { + ret = alloc_pages_bulk_array(GFP_KERNEL, pages, + rqstp->rq_pages); + if (ret > filled) + /* Made progress, don't sleep yet */ + continue;

set_current_state(TASK_INTERRUPTIBLE); if (signalled() || kthread_should_stop()) {