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| author |   Matthew Wilcox <willy@infradead.org> | 2018-11-16 15:19:13 -0500 |
|---|---|---|
| committer | Matthew Wilcox <willy@infradead.org> | 2018-11-17 12:07:53 -0500 |
| commit | 0e40de0338d005f73d46898a21544cd26f01b4ce (patch) | |
| tree | 219460210db66a66308167398ddc320252e30047 /fs | |
| parent | dax: Fix dax_unlock_mapping_entry for PMD pages (diff) | |
| download | linux-dev-0e40de0338d005f73d46898a21544cd26f01b4ce.tar.xz linux-dev-0e40de0338d005f73d46898a21544cd26f01b4ce.zip | |
dax: Fix huge page faults
Using xas_load() with a PMD-sized xa_state would work if either a
PMD-sized entry was present or a PTE sized entry was present in the
first 64 entries (of the 512 PTEs in a PMD on x86). If there was no
PTE in the first 64 entries, grab_mapping_entry() would believe there
were no entries present, allocate a PMD-sized entry and overwrite the
PTE in the page cache.
Use xas_find_conflict() instead which turns out to simplify
both get_unlocked_entry() and grab_mapping_entry(). Also remove a
WARN_ON_ONCE from grab_mapping_entry() as it will have already triggered
in get_unlocked_entry().
Fixes: cfc93c6c6c96 ("dax: Convert dax_insert_pfn_mkwrite to XArray")
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/dax.c | 12 |
1 files changed, 4 insertions, 8 deletions
@@ -216,9 +216,8 @@ static void *get_unlocked_entry(struct xa_state *xas) ewait.wait.func = wake_exceptional_entry_func; for (;;) { - entry = xas_load(xas); - if (!entry || xa_is_internal(entry) || - WARN_ON_ONCE(!xa_is_value(entry)) || + entry = xas_find_conflict(xas); + if (!entry || WARN_ON_ONCE(!xa_is_value(entry)) || !dax_is_locked(entry)) return entry; @@ -458,11 +457,9 @@ static void *grab_mapping_entry(struct xa_state *xas, retry: xas_lock_irq(xas); entry = get_unlocked_entry(xas); - if (xa_is_internal(entry)) - goto fallback; if (entry) { - if (WARN_ON_ONCE(!xa_is_value(entry))) { + if (!xa_is_value(entry)) { xas_set_err(xas, EIO); goto out_unlock; } @@ -1641,8 +1638,7 @@ dax_insert_pfn_mkwrite(struct vm_fault *vmf, pfn_t pfn, unsigned int order) /* Did we race with someone splitting entry or so? */ if (!entry || (order == 0 && !dax_is_pte_entry(entry)) || - (order == PMD_ORDER && (xa_is_internal(entry) || - !dax_is_pmd_entry(entry)))) { + (order == PMD_ORDER && !dax_is_pmd_entry(entry))) { put_unlocked_entry(&xas, entry); xas_unlock_irq(&xas); trace_dax_insert_pfn_mkwrite_no_entry(mapping->host, vmf, |