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6840f9094f
When UBSAN is enabled, it reports an invalid value in __pagevec_release()
when accessing pvec->percpu_pvec_drained, which is simply whatever
garbage was on the stack. Initialise it when initialising the rest of
the folio_batch.
Fixes: 10331795fb ("pagevec: Add folio_batch")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
150 lines
3.8 KiB
C
150 lines
3.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* include/linux/pagevec.h
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*
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* In many places it is efficient to batch an operation up against multiple
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* pages. A pagevec is a multipage container which is used for that.
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*/
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#ifndef _LINUX_PAGEVEC_H
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#define _LINUX_PAGEVEC_H
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#include <linux/xarray.h>
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/* 15 pointers + header align the pagevec structure to a power of two */
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#define PAGEVEC_SIZE 15
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struct page;
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struct folio;
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struct address_space;
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/* Layout must match folio_batch */
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struct pagevec {
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unsigned char nr;
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bool percpu_pvec_drained;
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struct page *pages[PAGEVEC_SIZE];
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};
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void __pagevec_release(struct pagevec *pvec);
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void __pagevec_lru_add(struct pagevec *pvec);
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unsigned pagevec_lookup_range(struct pagevec *pvec,
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struct address_space *mapping,
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pgoff_t *start, pgoff_t end);
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static inline unsigned pagevec_lookup(struct pagevec *pvec,
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struct address_space *mapping,
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pgoff_t *start)
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{
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return pagevec_lookup_range(pvec, mapping, start, (pgoff_t)-1);
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}
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unsigned pagevec_lookup_range_tag(struct pagevec *pvec,
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struct address_space *mapping, pgoff_t *index, pgoff_t end,
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xa_mark_t tag);
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static inline unsigned pagevec_lookup_tag(struct pagevec *pvec,
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struct address_space *mapping, pgoff_t *index, xa_mark_t tag)
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{
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return pagevec_lookup_range_tag(pvec, mapping, index, (pgoff_t)-1, tag);
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}
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static inline void pagevec_init(struct pagevec *pvec)
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{
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pvec->nr = 0;
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pvec->percpu_pvec_drained = false;
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}
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static inline void pagevec_reinit(struct pagevec *pvec)
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{
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pvec->nr = 0;
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}
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static inline unsigned pagevec_count(struct pagevec *pvec)
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{
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return pvec->nr;
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}
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static inline unsigned pagevec_space(struct pagevec *pvec)
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{
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return PAGEVEC_SIZE - pvec->nr;
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}
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/*
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* Add a page to a pagevec. Returns the number of slots still available.
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*/
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static inline unsigned pagevec_add(struct pagevec *pvec, struct page *page)
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{
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pvec->pages[pvec->nr++] = page;
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return pagevec_space(pvec);
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}
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static inline void pagevec_release(struct pagevec *pvec)
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{
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if (pagevec_count(pvec))
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__pagevec_release(pvec);
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}
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/**
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* struct folio_batch - A collection of folios.
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*
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* The folio_batch is used to amortise the cost of retrieving and
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* operating on a set of folios. The order of folios in the batch may be
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* significant (eg delete_from_page_cache_batch()). Some users of the
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* folio_batch store "exceptional" entries in it which can be removed
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* by calling folio_batch_remove_exceptionals().
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*/
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struct folio_batch {
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unsigned char nr;
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bool percpu_pvec_drained;
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struct folio *folios[PAGEVEC_SIZE];
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};
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/* Layout must match pagevec */
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static_assert(sizeof(struct pagevec) == sizeof(struct folio_batch));
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static_assert(offsetof(struct pagevec, pages) ==
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offsetof(struct folio_batch, folios));
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/**
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* folio_batch_init() - Initialise a batch of folios
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* @fbatch: The folio batch.
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*
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* A freshly initialised folio_batch contains zero folios.
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*/
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static inline void folio_batch_init(struct folio_batch *fbatch)
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{
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fbatch->nr = 0;
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fbatch->percpu_pvec_drained = false;
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}
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static inline unsigned int folio_batch_count(struct folio_batch *fbatch)
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{
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return fbatch->nr;
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}
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static inline unsigned int fbatch_space(struct folio_batch *fbatch)
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{
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return PAGEVEC_SIZE - fbatch->nr;
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}
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/**
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* folio_batch_add() - Add a folio to a batch.
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* @fbatch: The folio batch.
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* @folio: The folio to add.
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*
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* The folio is added to the end of the batch.
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* The batch must have previously been initialised using folio_batch_init().
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*
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* Return: The number of slots still available.
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*/
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static inline unsigned folio_batch_add(struct folio_batch *fbatch,
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struct folio *folio)
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{
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fbatch->folios[fbatch->nr++] = folio;
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return fbatch_space(fbatch);
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}
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static inline void folio_batch_release(struct folio_batch *fbatch)
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{
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pagevec_release((struct pagevec *)fbatch);
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}
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void folio_batch_remove_exceptionals(struct folio_batch *fbatch);
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#endif /* _LINUX_PAGEVEC_H */
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