z3fold: limit use of stale list for allocation
Currently if z3fold couldn't find an unbuddied page it would first try to pull a page off the stale list. The problem with this approach is that we can't 100% guarantee that the page is not processed by the workqueue thread at the same time unless we run cancel_work_sync() on it, which we can't do if we're in an atomic context. So let's just limit stale list usage to non-atomic contexts only. Link: http://lkml.kernel.org/r/47ab51e7-e9c1-d30e-ab17-f734dbc3abce@gmail.com Signed-off-by: Vitaly Vul <vitaly.vul@sony.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: <Oleksiy.Avramchenko@sony.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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parent
605ca5ede7
commit
5c9bab592f
35
mm/z3fold.c
35
mm/z3fold.c
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@ -620,24 +620,27 @@ lookup:
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bud = FIRST;
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}
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spin_lock(&pool->stale_lock);
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zhdr = list_first_entry_or_null(&pool->stale,
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struct z3fold_header, buddy);
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/*
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* Before allocating a page, let's see if we can take one from the
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* stale pages list. cancel_work_sync() can sleep so we must make
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* sure it won't be called in case we're in atomic context.
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*/
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if (zhdr && (can_sleep || !work_pending(&zhdr->work))) {
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list_del(&zhdr->buddy);
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spin_unlock(&pool->stale_lock);
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if (can_sleep)
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page = NULL;
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if (can_sleep) {
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spin_lock(&pool->stale_lock);
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zhdr = list_first_entry_or_null(&pool->stale,
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struct z3fold_header, buddy);
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/*
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* Before allocating a page, let's see if we can take one from
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* the stale pages list. cancel_work_sync() can sleep so we
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* limit this case to the contexts where we can sleep
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*/
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if (zhdr) {
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list_del(&zhdr->buddy);
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spin_unlock(&pool->stale_lock);
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cancel_work_sync(&zhdr->work);
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page = virt_to_page(zhdr);
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} else {
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spin_unlock(&pool->stale_lock);
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page = alloc_page(gfp);
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page = virt_to_page(zhdr);
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} else {
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spin_unlock(&pool->stale_lock);
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}
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}
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if (!page)
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page = alloc_page(gfp);
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if (!page)
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return -ENOMEM;
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