Messages in this thread | | | Subject | Re: [PATCH] riscv: fix locking violation in page fault handler | From | Nikolay Borisov <> | Date | Tue, 7 May 2019 11:04:58 +0300 |
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On 7.05.19 г. 10:36 ч., Andreas Schwab wrote: > When a user mode process accesses an address in the vmalloc area > do_page_fault tries to unlock the mmap semaphore when it isn't locked. > > Signed-off-by: Andreas Schwab <schwab@suse.de> > --- > arch/riscv/mm/fault.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c > index 88401d5125bc..c51878e5a66a 100644 > --- a/arch/riscv/mm/fault.c > +++ b/arch/riscv/mm/fault.c > @@ -181,6 +181,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs) > up_read(&mm->mmap_sem); > /* User mode accesses just cause a SIGSEGV */ > if (user_mode(regs)) { > +bad_area_do_trap: > do_trap(regs, SIGSEGV, code, addr, tsk); > return; > } > @@ -230,7 +231,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs) > int index; > > if (user_mode(regs)) > - goto bad_area; > + goto bad_area_do_trap; > > /* > * Synchronize this task's top level page-table >
In this case I think it will be a lot cleaner if you just duplicated the do_trap call. On a slightly different note - is there any reason why do_page_fault is such a spaghetti mess? At the very least the code under no_context label could go into it's own function since it just kills the process and never returns? Furthermore the whole vmalloc_fault just cries for being factored out in a function, it's explicitly in it's own block.
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