From 2bcbeaefde2f0384d6ad351c151b1a9fe7791a0a Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 24 Jul 2019 08:52:52 +0200 Subject: mm/hmm: always return EBUSY for invalid ranges in hmm_range_{fault,snapshot} We should not have two different error codes for the same condition. EAGAIN must be reserved for the FAULT_FLAG_ALLOW_RETRY retry case and signals to the caller that the mmap_sem has been unlocked. Use EBUSY for the !valid case so that callers can get the locking right. Link: https://lore.kernel.org/r/20190724065258.16603-2-hch@lst.de Tested-by: Ralph Campbell Signed-off-by: Christoph Hellwig Reviewed-by: Ralph Campbell Reviewed-by: Jason Gunthorpe Reviewed-by: Felix Kuehling [jgg: elaborated commit message] Signed-off-by: Jason Gunthorpe --- Documentation/vm/hmm.rst | 2 +- mm/hmm.c | 10 ++++------ 2 files changed, 5 insertions(+), 7 deletions(-) diff --git a/Documentation/vm/hmm.rst b/Documentation/vm/hmm.rst index 7d90964abbb0..710ce1c701bf 100644 --- a/Documentation/vm/hmm.rst +++ b/Documentation/vm/hmm.rst @@ -237,7 +237,7 @@ The usage pattern is:: ret = hmm_range_snapshot(&range); if (ret) { up_read(&mm->mmap_sem); - if (ret == -EAGAIN) { + if (ret == -EBUSY) { /* * No need to check hmm_range_wait_until_valid() return value * on retry we will get proper error with hmm_range_snapshot() diff --git a/mm/hmm.c b/mm/hmm.c index e1eedef129cf..16b6731a34db 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -946,7 +946,7 @@ EXPORT_SYMBOL(hmm_range_unregister); * @range: range * Return: -EINVAL if invalid argument, -ENOMEM out of memory, -EPERM invalid * permission (for instance asking for write and range is read only), - * -EAGAIN if you need to retry, -EFAULT invalid (ie either no valid + * -EBUSY if you need to retry, -EFAULT invalid (ie either no valid * vma or it is illegal to access that range), number of valid pages * in range->pfns[] (from range start address). * @@ -967,7 +967,7 @@ long hmm_range_snapshot(struct hmm_range *range) do { /* If range is no longer valid force retry. */ if (!range->valid) - return -EAGAIN; + return -EBUSY; vma = find_vma(hmm->mm, start); if (vma == NULL || (vma->vm_flags & device_vma)) @@ -1062,10 +1062,8 @@ long hmm_range_fault(struct hmm_range *range, bool block) do { /* If range is no longer valid force retry. */ - if (!range->valid) { - up_read(&hmm->mm->mmap_sem); - return -EAGAIN; - } + if (!range->valid) + return -EBUSY; vma = find_vma(hmm->mm, start); if (vma == NULL || (vma->vm_flags & device_vma)) -- cgit v1.2.3