From be957c886d92aa9caf0f63aee2c77d1497217d93 Mon Sep 17 00:00:00 2001 From: Jason Gunthorpe Date: Fri, 1 May 2020 15:20:45 -0300 Subject: mm/hmm: make hmm_range_fault return 0 or -1 hmm_vma_walk->last is supposed to be updated after every write to the pfns, so that it can be returned by hmm_range_fault(). However, this is not done consistently. Fortunately nothing checks the return code of hmm_range_fault() for anything other than error. More importantly last must be set before returning -EBUSY as it is used to prevent reading an output pfn as an input flags when the loop restarts. For clarity and simplicity make hmm_range_fault() return 0 or -ERRNO. Only set last when returning -EBUSY. Link: https://lore.kernel.org/r/2-v2-b4e84f444c7d+24f57-hmm_no_flags_jgg@mellanox.com Acked-by: Felix Kuehling Tested-by: Ralph Campbell Reviewed-by: Christoph Hellwig Signed-off-by: Jason Gunthorpe --- Documentation/vm/hmm.rst | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'Documentation/vm') diff --git a/Documentation/vm/hmm.rst b/Documentation/vm/hmm.rst index 4e3e9362afeb..9924f2caa018 100644 --- a/Documentation/vm/hmm.rst +++ b/Documentation/vm/hmm.rst @@ -161,7 +161,7 @@ device must complete the update before the driver callback returns. When the device driver wants to populate a range of virtual addresses, it can use:: - long hmm_range_fault(struct hmm_range *range); + int hmm_range_fault(struct hmm_range *range); It will trigger a page fault on missing or read-only entries if write access is requested (see below). Page faults use the generic mm page fault code path just -- cgit v1.2.3