forked from luck/tmp_suning_uos_patched
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: cfc93c6c6c
("dax: Convert dax_insert_pfn_mkwrite to XArray")
Signed-off-by: Matthew Wilcox <willy@infradead.org>
This commit is contained in:
parent
fda490d39f
commit
0e40de0338
12
fs/dax.c
12
fs/dax.c
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@ -216,9 +216,8 @@ static void *get_unlocked_entry(struct xa_state *xas)
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ewait.wait.func = wake_exceptional_entry_func;
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for (;;) {
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entry = xas_load(xas);
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if (!entry || xa_is_internal(entry) ||
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WARN_ON_ONCE(!xa_is_value(entry)) ||
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entry = xas_find_conflict(xas);
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if (!entry || WARN_ON_ONCE(!xa_is_value(entry)) ||
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!dax_is_locked(entry))
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return entry;
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@ -458,11 +457,9 @@ static void *grab_mapping_entry(struct xa_state *xas,
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retry:
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xas_lock_irq(xas);
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entry = get_unlocked_entry(xas);
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if (xa_is_internal(entry))
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goto fallback;
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if (entry) {
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if (WARN_ON_ONCE(!xa_is_value(entry))) {
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if (!xa_is_value(entry)) {
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xas_set_err(xas, EIO);
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goto out_unlock;
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}
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@ -1641,8 +1638,7 @@ dax_insert_pfn_mkwrite(struct vm_fault *vmf, pfn_t pfn, unsigned int order)
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/* Did we race with someone splitting entry or so? */
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if (!entry ||
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(order == 0 && !dax_is_pte_entry(entry)) ||
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(order == PMD_ORDER && (xa_is_internal(entry) ||
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!dax_is_pmd_entry(entry)))) {
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(order == PMD_ORDER && !dax_is_pmd_entry(entry))) {
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put_unlocked_entry(&xas, entry);
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xas_unlock_irq(&xas);
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trace_dax_insert_pfn_mkwrite_no_entry(mapping->host, vmf,
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