readahead: fault retry breaks mmap file read random detection
.fault now can retry. The retry can break state machine of .fault. In filemap_fault, if page is miss, ra->mmap_miss is increased. In the second try, since the page is in page cache now, ra->mmap_miss is decreased. And these are done in one fault, so we can't detect random mmap file access. Add a new flag to indicate .fault is tried once. In the second try, skip ra->mmap_miss decreasing. The filemap_fault state machine is ok with it. I only tested x86, didn't test other archs, but looks the change for other archs is obvious, but who knows :) Signed-off-by: Shaohua Li <shaohua.li@fusionio.com> Cc: Rik van Riel <riel@redhat.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
parent
e79bee24fd
commit
45cac65b0f
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@ -336,6 +336,7 @@ retry:
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/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
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/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
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* of starvation. */
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* of starvation. */
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags |= FAULT_FLAG_TRIED;
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goto retry;
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goto retry;
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}
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}
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}
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}
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@ -152,6 +152,7 @@ good_area:
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tsk->min_flt++;
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tsk->min_flt++;
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if (fault & VM_FAULT_RETRY) {
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if (fault & VM_FAULT_RETRY) {
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags |= FAULT_FLAG_TRIED;
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/*
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/*
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* No need to up_read(&mm->mmap_sem) as we would have
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* No need to up_read(&mm->mmap_sem) as we would have
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@ -186,6 +186,7 @@ retry:
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tsk->min_flt++;
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tsk->min_flt++;
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if (fault & VM_FAULT_RETRY) {
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if (fault & VM_FAULT_RETRY) {
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags |= FAULT_FLAG_TRIED;
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/*
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/*
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* No need to up_read(&mm->mmap_sem) as we would
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* No need to up_read(&mm->mmap_sem) as we would
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@ -113,6 +113,7 @@ good_area:
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current->min_flt++;
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current->min_flt++;
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if (fault & VM_FAULT_RETRY) {
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if (fault & VM_FAULT_RETRY) {
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags |= FAULT_FLAG_TRIED;
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goto retry;
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goto retry;
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}
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}
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}
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}
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@ -184,6 +184,7 @@ retry:
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current->min_flt++;
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current->min_flt++;
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if (fault & VM_FAULT_RETRY) {
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if (fault & VM_FAULT_RETRY) {
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags |= FAULT_FLAG_TRIED;
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/* No need to up_read(&mm->mmap_sem) as we would
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/* No need to up_read(&mm->mmap_sem) as we would
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* have already released it in __lock_page_or_retry
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* have already released it in __lock_page_or_retry
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@ -170,6 +170,7 @@ good_area:
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/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
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/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
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* of starvation. */
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* of starvation. */
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags |= FAULT_FLAG_TRIED;
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/*
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/*
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* No need to up_read(&mm->mmap_sem) as we would
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* No need to up_read(&mm->mmap_sem) as we would
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@ -233,6 +233,7 @@ good_area:
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current->min_flt++;
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current->min_flt++;
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if (fault & VM_FAULT_RETRY) {
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if (fault & VM_FAULT_RETRY) {
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags |= FAULT_FLAG_TRIED;
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/*
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/*
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* No need to up_read(&mm->mmap_sem) as we would
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* No need to up_read(&mm->mmap_sem) as we would
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@ -171,6 +171,7 @@ good_area:
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}
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}
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if (fault & VM_FAULT_RETRY) {
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if (fault & VM_FAULT_RETRY) {
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags |= FAULT_FLAG_TRIED;
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/*
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/*
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* No need to up_read(&mm->mmap_sem) as we would
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* No need to up_read(&mm->mmap_sem) as we would
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@ -183,6 +183,7 @@ good_area:
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tsk->min_flt++;
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tsk->min_flt++;
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if (fault & VM_FAULT_RETRY) {
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if (fault & VM_FAULT_RETRY) {
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags |= FAULT_FLAG_TRIED;
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/* No need to up_read(&mm->mmap_sem) as we would
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/* No need to up_read(&mm->mmap_sem) as we would
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* have already released it in __lock_page_or_retry
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* have already released it in __lock_page_or_retry
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@ -451,6 +451,7 @@ good_area:
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/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
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/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
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* of starvation. */
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* of starvation. */
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags |= FAULT_FLAG_TRIED;
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goto retry;
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goto retry;
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}
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}
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}
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}
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@ -367,6 +367,7 @@ retry:
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/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
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/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
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* of starvation. */
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* of starvation. */
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags |= FAULT_FLAG_TRIED;
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down_read(&mm->mmap_sem);
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down_read(&mm->mmap_sem);
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goto retry;
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goto retry;
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}
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}
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@ -504,6 +504,7 @@ good_area:
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}
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}
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if (fault & VM_FAULT_RETRY) {
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if (fault & VM_FAULT_RETRY) {
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags |= FAULT_FLAG_TRIED;
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/*
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/*
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* No need to up_read(&mm->mmap_sem) as we would
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* No need to up_read(&mm->mmap_sem) as we would
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@ -265,6 +265,7 @@ good_area:
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}
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}
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if (fault & VM_FAULT_RETRY) {
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if (fault & VM_FAULT_RETRY) {
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags |= FAULT_FLAG_TRIED;
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/* No need to up_read(&mm->mmap_sem) as we would
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/* No need to up_read(&mm->mmap_sem) as we would
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* have already released it in __lock_page_or_retry
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* have already released it in __lock_page_or_retry
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@ -452,6 +452,7 @@ good_area:
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}
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}
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if (fault & VM_FAULT_RETRY) {
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if (fault & VM_FAULT_RETRY) {
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags |= FAULT_FLAG_TRIED;
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/* No need to up_read(&mm->mmap_sem) as we would
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/* No need to up_read(&mm->mmap_sem) as we would
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* have already released it in __lock_page_or_retry
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* have already released it in __lock_page_or_retry
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@ -454,6 +454,7 @@ good_area:
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tsk->min_flt++;
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tsk->min_flt++;
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if (fault & VM_FAULT_RETRY) {
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if (fault & VM_FAULT_RETRY) {
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags |= FAULT_FLAG_TRIED;
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/*
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/*
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* No need to up_read(&mm->mmap_sem) as we would
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* No need to up_read(&mm->mmap_sem) as we would
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@ -89,6 +89,7 @@ good_area:
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current->min_flt++;
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current->min_flt++;
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if (fault & VM_FAULT_RETRY) {
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if (fault & VM_FAULT_RETRY) {
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags |= FAULT_FLAG_TRIED;
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goto retry;
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goto retry;
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}
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}
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@ -1220,6 +1220,7 @@ good_area:
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/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
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/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
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* of starvation. */
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* of starvation. */
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags |= FAULT_FLAG_TRIED;
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goto retry;
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goto retry;
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}
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}
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}
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}
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@ -126,6 +126,7 @@ good_area:
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current->min_flt++;
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current->min_flt++;
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if (fault & VM_FAULT_RETRY) {
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if (fault & VM_FAULT_RETRY) {
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags |= FAULT_FLAG_TRIED;
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/* No need to up_read(&mm->mmap_sem) as we would
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/* No need to up_read(&mm->mmap_sem) as we would
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* have already released it in __lock_page_or_retry
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* have already released it in __lock_page_or_retry
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@ -161,6 +161,7 @@ extern pgprot_t protection_map[16];
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#define FAULT_FLAG_ALLOW_RETRY 0x08 /* Retry fault if blocking */
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#define FAULT_FLAG_ALLOW_RETRY 0x08 /* Retry fault if blocking */
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#define FAULT_FLAG_RETRY_NOWAIT 0x10 /* Don't drop mmap_sem and wait when retrying */
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#define FAULT_FLAG_RETRY_NOWAIT 0x10 /* Don't drop mmap_sem and wait when retrying */
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#define FAULT_FLAG_KILLABLE 0x20 /* The fault task is in SIGKILL killable region */
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#define FAULT_FLAG_KILLABLE 0x20 /* The fault task is in SIGKILL killable region */
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#define FAULT_FLAG_TRIED 0x40 /* second try */
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/*
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/*
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* vm_fault is filled by the the pagefault handler and passed to the vma's
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* vm_fault is filled by the the pagefault handler and passed to the vma's
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@ -1607,13 +1607,13 @@ int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
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* Do we have something in the page cache already?
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* Do we have something in the page cache already?
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*/
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*/
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page = find_get_page(mapping, offset);
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page = find_get_page(mapping, offset);
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if (likely(page)) {
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if (likely(page) && !(vmf->flags & FAULT_FLAG_TRIED)) {
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/*
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/*
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* We found the page, so try async readahead before
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* We found the page, so try async readahead before
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* waiting for the lock.
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* waiting for the lock.
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*/
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*/
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do_async_mmap_readahead(vma, ra, file, page, offset);
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do_async_mmap_readahead(vma, ra, file, page, offset);
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} else {
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} else if (!page) {
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/* No page in the page cache at all */
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/* No page in the page cache at all */
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do_sync_mmap_readahead(vma, ra, file, offset);
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do_sync_mmap_readahead(vma, ra, file, offset);
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count_vm_event(PGMAJFAULT);
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count_vm_event(PGMAJFAULT);
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