From mboxrd@z Thu Jan 1 00:00:00 1970 From: Khalid Aziz Subject: [RFC PATCH v7 15/16] xpfo, mm: Fix hang when booting with "xpfotlbflush" Date: Thu, 10 Jan 2019 14:09:47 -0700 Message-Id: In-Reply-To: References: In-Reply-To: References: To: juergh@gmail.com, tycho@tycho.ws, jsteckli@amazon.de, ak@linux.intel.com, torvalds@linux-foundation.org, liran.alon@oracle.com, keescook@google.com, konrad.wilk@oracle.com Cc: Khalid Aziz , deepa.srinivasan@oracle.com, chris.hyser@oracle.com, tyhicks@canonical.com, dwmw@amazon.co.uk, andrew.cooper3@citrix.com, jcm@redhat.com, boris.ostrovsky@oracle.com, kanth.ghatraju@oracle.com, joao.m.martins@oracle.com, jmattson@google.com, pradeep.vincent@oracle.com, john.haxby@oracle.com, tglx@linutronix.de, kirill.shutemov@linux.intel.com, hch@lst.de, steven.sistare@oracle.com, kernel-hardening@lists.openwall.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: Kernel hangs when booted up with "xpfotlbflush" option. This is caused by xpfo_kunmap() fliushing TLB while holding xpfo lock starving other tasks waiting for the lock. This patch moves tlb flush outside of the code holding xpfo lock. Signed-off-by: Khalid Aziz --- mm/xpfo.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/mm/xpfo.c b/mm/xpfo.c index 85079377c91d..79ffdba6af69 100644 --- a/mm/xpfo.c +++ b/mm/xpfo.c @@ -148,6 +148,8 @@ EXPORT_SYMBOL(xpfo_kmap); void xpfo_kunmap(void *kaddr, struct page *page) { + bool flush_tlb = false; + if (!static_branch_unlikely(&xpfo_inited)) return; @@ -168,10 +170,13 @@ void xpfo_kunmap(void *kaddr, struct page *page) if (atomic_read(&page->xpfo_mapcount) == 0) { SetPageXpfoUnmapped(page); set_kpte(kaddr, page, __pgprot(0)); - xpfo_cond_flush_kernel_tlb(page, 0); + flush_tlb = true; } spin_unlock(&page->xpfo_lock); } + + if (flush_tlb) + xpfo_cond_flush_kernel_tlb(page, 0); } EXPORT_SYMBOL(xpfo_kunmap); -- 2.17.1