summaryrefslogtreecommitdiffstats
path: root/mm/hmm.c
diff options
context:
space:
mode:
authorJason Gunthorpe <jgg@mellanox.com>2020-02-28 15:52:32 -0400
committerJason Gunthorpe <jgg@mellanox.com>2020-03-26 14:33:37 -0300
commit76612d6ce4ccd21329ce8c90dc51c5f747057b5b (patch)
treeaaa860ad6fe429eebeae49147858ff4c783d73f1 /mm/hmm.c
parentc2579c9c4add3110b2ce81198f8a6bbb5055cfda (diff)
downloadlinux-76612d6ce4ccd21329ce8c90dc51c5f747057b5b.tar.gz
linux-76612d6ce4ccd21329ce8c90dc51c5f747057b5b.tar.bz2
linux-76612d6ce4ccd21329ce8c90dc51c5f747057b5b.zip
mm/hmm: reorganize how !pte_present is handled in hmm_vma_handle_pte()
The intention with this code is to determine if the caller required the pages to be valid, and if so, then take some action to make them valid. The action varies depending on the page type. In all cases, if the caller doesn't ask for the page, then hmm_range_fault() should not return an error. Revise the implementation to be clearer, and fix some bugs: - hmm_pte_need_fault() must always be called before testing fault or write_fault otherwise the defaults of false apply and the if()'s don't work. This was missed on the is_migration_entry() branch - -EFAULT should not be returned unless hmm_pte_need_fault() indicates fault is required - ie snapshotting should not fail. - For !pte_present() the cpu_flags are always 0, except in the special case of is_device_private_entry(), calling pte_to_hmm_pfn_flags() is confusing. Reorganize the flow so that it always follows the pattern of calling hmm_pte_need_fault() and then checking fault || write_fault. Fixes: 2aee09d8c116 ("mm/hmm: change hmm_vma_fault() to allow write fault on page basis") Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Diffstat (limited to 'mm/hmm.c')
-rw-r--r--mm/hmm.c35
1 files changed, 15 insertions, 20 deletions
diff --git a/mm/hmm.c b/mm/hmm.c
index a16b8e360e4c..b98f492984e5 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -286,15 +286,6 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
if (!pte_present(pte)) {
swp_entry_t entry = pte_to_swp_entry(pte);
- if (!non_swap_entry(entry)) {
- cpu_flags = pte_to_hmm_pfn_flags(range, pte);
- hmm_pte_need_fault(hmm_vma_walk, orig_pfn, cpu_flags,
- &fault, &write_fault);
- if (fault || write_fault)
- goto fault;
- return 0;
- }
-
/*
* This is a special swap entry, ignore migration, use
* device and report anything else as error.
@@ -314,26 +305,30 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
return 0;
}
- if (is_migration_entry(entry)) {
- if (fault || write_fault) {
- pte_unmap(ptep);
- hmm_vma_walk->last = addr;
- migration_entry_wait(walk->mm, pmdp, addr);
- return -EBUSY;
- }
+ hmm_pte_need_fault(hmm_vma_walk, orig_pfn, 0, &fault,
+ &write_fault);
+ if (!fault && !write_fault)
return 0;
+
+ if (!non_swap_entry(entry))
+ goto fault;
+
+ if (is_migration_entry(entry)) {
+ pte_unmap(ptep);
+ hmm_vma_walk->last = addr;
+ migration_entry_wait(walk->mm, pmdp, addr);
+ return -EBUSY;
}
/* Report error for everything else */
pte_unmap(ptep);
*pfn = range->values[HMM_PFN_ERROR];
return -EFAULT;
- } else {
- cpu_flags = pte_to_hmm_pfn_flags(range, pte);
- hmm_pte_need_fault(hmm_vma_walk, orig_pfn, cpu_flags,
- &fault, &write_fault);
}
+ cpu_flags = pte_to_hmm_pfn_flags(range, pte);
+ hmm_pte_need_fault(hmm_vma_walk, orig_pfn, cpu_flags, &fault,
+ &write_fault);
if (fault || write_fault)
goto fault;