From: Paolo 'Blaisorblade' Giarrusso Date: Fri, 23 Sep 2005 04:44:20 +0000 (-0700) Subject: [PATCH] uml: avoid fixing faults while atomic X-Git-Tag: Ubuntu-5.0.0-8.9~54158^2~55 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=fea03cb40a15e3c6647c0927300202e062e6792a;p=mirror_ubuntu-disco-kernel.git [PATCH] uml: avoid fixing faults while atomic Following i386, we should maybe refuse trying to fault in pages when we're doing atomic operations, because to handle the fault we could need to take already taken spinlocks. Also, if we're doing an atomic operation (in the sense of in_atomic()) we're surely in kernel mode and we're surely going to handle adequately the failed fault, so it's safe to behave this way. Currently, on UML SMP is rarely used, and we don't support PREEMPT, so this is unlikely to create problems right now, but it might in the future. Signed-off-by: Paolo 'Blaisorblade' Giarrusso Cc: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/arch/um/kernel/trap_kern.c b/arch/um/kernel/trap_kern.c index 90690b9b1f30..d297429ac360 100644 --- a/arch/um/kernel/trap_kern.c +++ b/arch/um/kernel/trap_kern.c @@ -40,6 +40,12 @@ int handle_page_fault(unsigned long address, unsigned long ip, int err = -EFAULT; *code_out = SEGV_MAPERR; + + /* If the fault was during atomic operation, don't take the fault, just + * fail. */ + if (in_atomic()) + goto out_nosemaphore; + down_read(&mm->mmap_sem); vma = find_vma(mm, address); if(!vma) @@ -90,6 +96,7 @@ survive: flush_tlb_page(vma, address); out: up_read(&mm->mmap_sem); +out_nosemaphore: return(err); /*