From: Christoph Hellwig <hch@xxxxxx> [ Upstream commit 2bcbeaefde2f0384d6ad351c151b1a9fe7791a0a ] 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@xxxxxx Tested-by: Ralph Campbell <rcampbell@xxxxxxxxxx> Signed-off-by: Christoph Hellwig <hch@xxxxxx> Reviewed-by: Ralph Campbell <rcampbell@xxxxxxxxxx> Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx> Reviewed-by: Felix Kuehling <Felix.Kuehling@xxxxxxx> [jgg: elaborated commit message] Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- 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 7cdf7282e0229..65b6c1109cc81 100644 --- a/Documentation/vm/hmm.rst +++ b/Documentation/vm/hmm.rst @@ -231,7 +231,7 @@ respect in order to keep things properly synchronized. 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 4c405dfbd2b3d..27dd9a8816272 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -995,7 +995,7 @@ EXPORT_SYMBOL(hmm_range_unregister); * @range: range * Returns: -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). * @@ -1019,7 +1019,7 @@ long hmm_range_snapshot(struct hmm_range *range) do { /* If range is no longer valid force retry.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& device_vma)) @@ -1117,10 +1117,8 @@ long hmm_range_fault(struct hmm_range *range, bool block) do { /* If range is no longer valid force retry.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)) -- 2.20.1
