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Diffstat (limited to 'mm/filemap.c')
-rw-r--r--mm/filemap.c305
1 files changed, 197 insertions, 108 deletions
diff --git a/mm/filemap.c b/mm/filemap.c
index a30dbf93de99..4920d32b1edd 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -36,6 +36,8 @@
#include <linux/memcontrol.h>
#include <linux/cleancache.h>
#include <linux/rmap.h>
+#include <linux/delayacct.h>
+#include <linux/psi.h>
#include "internal.h"
#define CREATE_TRACE_POINTS
@@ -421,19 +423,17 @@ static void __filemap_fdatawait_range(struct address_space *mapping,
return;
pagevec_init(&pvec, 0);
- while ((index <= end) &&
- (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
- PAGECACHE_TAG_WRITEBACK,
- min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
+ while (index <= end) {
unsigned i;
+ nr_pages = pagevec_lookup_range_tag(&pvec, mapping, &index,
+ end, PAGECACHE_TAG_WRITEBACK);
+ if (!nr_pages)
+ break;
+
for (i = 0; i < nr_pages; i++) {
struct page *page = pvec.pages[i];
- /* until radix tree lookup accepts end_index */
- if (page->index > end)
- continue;
-
wait_on_page_writeback(page);
ClearPageError(page);
}
@@ -840,12 +840,9 @@ int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
* data from the working set, only to cache data that will
* get overwritten with something else, is a waste of memory.
*/
- if (!(gfp_mask & __GFP_WRITE) &&
- shadow && workingset_refault(shadow)) {
- SetPageActive(page);
- workingset_activation(page);
- } else
- ClearPageActive(page);
+ WARN_ON_ONCE(PageActive(page));
+ if (!(gfp_mask & __GFP_WRITE) && shadow)
+ workingset_refault(page, shadow);
lru_cache_add(page);
}
return ret;
@@ -1001,8 +998,18 @@ static inline int wait_on_page_bit_common(wait_queue_head_t *q,
{
struct wait_page_queue wait_page;
wait_queue_entry_t *wait = &wait_page.wait;
+ bool thrashing = false;
+ unsigned long pflags;
int ret = 0;
+ if (bit_nr == PG_locked &&
+ !PageUptodate(page) && PageWorkingset(page)) {
+ if (!PageSwapBacked(page))
+ delayacct_thrashing_start();
+ psi_memstall_enter(&pflags);
+ thrashing = true;
+ }
+
init_wait(wait);
wait->flags = lock ? WQ_FLAG_EXCLUSIVE : 0;
wait->func = wake_page_function;
@@ -1041,6 +1048,12 @@ static inline int wait_on_page_bit_common(wait_queue_head_t *q,
finish_wait(q, wait);
+ if (thrashing) {
+ if (!PageSwapBacked(page))
+ delayacct_thrashing_end();
+ psi_memstall_leave(&pflags);
+ }
+
/*
* A signal could leave PageWaiters set. Clearing it here if
* !waitqueue_active would be possible (by open-coding finish_wait),
@@ -1449,7 +1462,10 @@ EXPORT_SYMBOL(find_lock_entry);
* - FGP_CREAT: If page is not present then a new page is allocated using
* @gfp_mask and added to the page cache and the VM's LRU
* list. The page is returned locked and with an increased
- * refcount. Otherwise, NULL is returned.
+ * refcount.
+ * - FGP_FOR_MMAP: Similar to FGP_CREAT, only we want to allow the caller to do
+ * its own locking dance if the page is already in cache, or unlock the page
+ * before returning if we had to add the page to pagecache.
*
* If FGP_LOCK or FGP_CREAT are specified then the function may sleep even
* if the GFP flags specified for FGP_CREAT are atomic.
@@ -1502,7 +1518,7 @@ no_page:
if (!page)
return NULL;
- if (WARN_ON_ONCE(!(fgp_flags & FGP_LOCK)))
+ if (WARN_ON_ONCE(!(fgp_flags & (FGP_LOCK | FGP_FOR_MMAP))))
fgp_flags |= FGP_LOCK;
/* Init accessed so avoid atomic mark_page_accessed later */
@@ -1516,6 +1532,13 @@ no_page:
if (err == -EEXIST)
goto repeat;
}
+
+ /*
+ * add_to_page_cache_lru locks the page, and for mmap we expect
+ * an unlocked page.
+ */
+ if (page && (fgp_flags & FGP_FOR_MMAP))
+ unlock_page(page);
}
return page;
@@ -1776,9 +1799,10 @@ repeat:
EXPORT_SYMBOL(find_get_pages_contig);
/**
- * find_get_pages_tag - find and return pages that match @tag
+ * find_get_pages_range_tag - find and return pages in given range matching @tag
* @mapping: the address_space to search
* @index: the starting page index
+ * @end: The final page index (inclusive)
* @tag: the tag index
* @nr_pages: the maximum number of pages
* @pages: where the resulting pages are placed
@@ -1786,8 +1810,9 @@ EXPORT_SYMBOL(find_get_pages_contig);
* Like find_get_pages, except we only return pages which are tagged with
* @tag. We update @index to index the next page for the traversal.
*/
-unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
- int tag, unsigned int nr_pages, struct page **pages)
+unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index,
+ pgoff_t end, int tag, unsigned int nr_pages,
+ struct page **pages)
{
struct radix_tree_iter iter;
void **slot;
@@ -1800,6 +1825,9 @@ unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
radix_tree_for_each_tagged(slot, &mapping->page_tree,
&iter, *index, tag) {
struct page *head, *page;
+
+ if (iter.index > end)
+ break;
repeat:
page = radix_tree_deref_slot(slot);
if (unlikely(!page))
@@ -1841,18 +1869,28 @@ repeat:
}
pages[ret] = page;
- if (++ret == nr_pages)
- break;
+ if (++ret == nr_pages) {
+ *index = pages[ret - 1]->index + 1;
+ goto out;
+ }
}
+ /*
+ * We come here when we got at @end. We take care to not overflow the
+ * index @index as it confuses some of the callers. This breaks the
+ * iteration when there is page at index -1 but that is already broken
+ * anyway.
+ */
+ if (end == (pgoff_t)-1)
+ *index = (pgoff_t)-1;
+ else
+ *index = end + 1;
+out:
rcu_read_unlock();
- if (ret)
- *index = pages[ret - 1]->index + 1;
-
return ret;
}
-EXPORT_SYMBOL(find_get_pages_tag);
+EXPORT_SYMBOL(find_get_pages_range_tag);
/**
* find_get_entries_tag - find and return entries that match @tag
@@ -2277,62 +2315,98 @@ out:
EXPORT_SYMBOL(generic_file_read_iter);
#ifdef CONFIG_MMU
-/**
- * page_cache_read - adds requested page to the page cache if not already there
- * @file: file to read
- * @offset: page index
- * @gfp_mask: memory allocation flags
- *
- * This adds the requested page to the page cache if it isn't already there,
- * and schedules an I/O to read in its contents from disk.
- */
-static int page_cache_read(struct file *file, pgoff_t offset, gfp_t gfp_mask)
+#define MMAP_LOTSAMISS (100)
+static struct file *maybe_unlock_mmap_for_io(struct vm_fault *vmf,
+ struct file *fpin)
{
- struct address_space *mapping = file->f_mapping;
- struct page *page;
- int ret;
+ int flags = vmf->flags;
- do {
- page = __page_cache_alloc(gfp_mask|__GFP_COLD);
- if (!page)
- return -ENOMEM;
+ if (fpin)
+ return fpin;
- ret = add_to_page_cache_lru(page, mapping, offset, gfp_mask);
- if (ret == 0)
- ret = mapping->a_ops->readpage(file, page);
- else if (ret == -EEXIST)
- ret = 0; /* losing race to add is OK */
+ /*
+ * FAULT_FLAG_RETRY_NOWAIT means we don't want to wait on page locks or
+ * anything, so we only pin the file and drop the mmap_sem if only
+ * FAULT_FLAG_ALLOW_RETRY is set.
+ */
+ if ((flags & (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT)) ==
+ FAULT_FLAG_ALLOW_RETRY) {
+ fpin = get_file(vmf->vma->vm_file);
+ up_read(&vmf->vma->vm_mm->mmap_sem);
+ }
+ return fpin;
+}
- put_page(page);
+/*
+ * lock_page_maybe_drop_mmap - lock the page, possibly dropping the mmap_sem
+ * @vmf - the vm_fault for this fault.
+ * @page - the page to lock.
+ * @fpin - the pointer to the file we may pin (or is already pinned).
+ *
+ * This works similar to lock_page_or_retry in that it can drop the mmap_sem.
+ * It differs in that it actually returns the page locked if it returns 1 and 0
+ * if it couldn't lock the page. If we did have to drop the mmap_sem then fpin
+ * will point to the pinned file and needs to be fput()'ed at a later point.
+ */
+static int lock_page_maybe_drop_mmap(struct vm_fault *vmf, struct page *page,
+ struct file **fpin)
+{
+ if (trylock_page(page))
+ return 1;
- } while (ret == AOP_TRUNCATED_PAGE);
+ /*
+ * NOTE! This will make us return with VM_FAULT_RETRY, but with
+ * the mmap_sem still held. That's how FAULT_FLAG_RETRY_NOWAIT
+ * is supposed to work. We have way too many special cases..
+ */
+ if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT)
+ return 0;
- return ret;
+ *fpin = maybe_unlock_mmap_for_io(vmf, *fpin);
+ if (vmf->flags & FAULT_FLAG_KILLABLE) {
+ if (__lock_page_killable(page)) {
+ /*
+ * We didn't have the right flags to drop the mmap_sem,
+ * but all fault_handlers only check for fatal signals
+ * if we return VM_FAULT_RETRY, so we need to drop the
+ * mmap_sem here and return 0 if we don't have a fpin.
+ */
+ if (*fpin == NULL)
+ up_read(&vmf->vma->vm_mm->mmap_sem);
+ return 0;
+ }
+ } else
+ __lock_page(page);
+ return 1;
}
-#define MMAP_LOTSAMISS (100)
/*
- * Synchronous readahead happens when we don't even find
- * a page in the page cache at all.
+ * Synchronous readahead happens when we don't even find a page in the page
+ * cache at all. We don't want to perform IO under the mmap sem, so if we have
+ * to drop the mmap sem we return the file that was pinned in order for us to do
+ * that. If we didn't pin a file then we return NULL. The file that is
+ * returned needs to be fput()'ed when we're done with it.
*/
-static void do_sync_mmap_readahead(struct vm_area_struct *vma,
- struct file_ra_state *ra,
- struct file *file,
- pgoff_t offset)
+static struct file *do_sync_mmap_readahead(struct vm_fault *vmf)
{
+ struct file *file = vmf->vma->vm_file;
+ struct file_ra_state *ra = &file->f_ra;
struct address_space *mapping = file->f_mapping;
+ struct file *fpin = NULL;
+ pgoff_t offset = vmf->pgoff;
/* If we don't want any read-ahead, don't bother */
- if (vma->vm_flags & VM_RAND_READ)
- return;
+ if (vmf->vma->vm_flags & VM_RAND_READ)
+ return fpin;
if (!ra->ra_pages)
- return;
+ return fpin;
- if (vma->vm_flags & VM_SEQ_READ) {
+ if (vmf->vma->vm_flags & VM_SEQ_READ) {
+ fpin = maybe_unlock_mmap_for_io(vmf, fpin);
page_cache_sync_readahead(mapping, ra, file, offset,
ra->ra_pages);
- return;
+ return fpin;
}
/* Avoid banging the cache line if not needed */
@@ -2344,37 +2418,44 @@ static void do_sync_mmap_readahead(struct vm_area_struct *vma,
* stop bothering with read-ahead. It will only hurt.
*/
if (ra->mmap_miss > MMAP_LOTSAMISS)
- return;
+ return fpin;
/*
* mmap read-around
*/
+ fpin = maybe_unlock_mmap_for_io(vmf, fpin);
ra->start = max_t(long, 0, offset - ra->ra_pages / 2);
ra->size = ra->ra_pages;
ra->async_size = ra->ra_pages / 4;
ra_submit(ra, mapping, file);
+ return fpin;
}
/*
* Asynchronous readahead happens when we find the page and PG_readahead,
- * so we want to possibly extend the readahead further..
+ * so we want to possibly extend the readahead further. We return the file that
+ * was pinned if we have to drop the mmap_sem in order to do IO.
*/
-static void do_async_mmap_readahead(struct vm_area_struct *vma,
- struct file_ra_state *ra,
- struct file *file,
- struct page *page,
- pgoff_t offset)
+static struct file *do_async_mmap_readahead(struct vm_fault *vmf,
+ struct page *page)
{
+ struct file *file = vmf->vma->vm_file;
+ struct file_ra_state *ra = &file->f_ra;
struct address_space *mapping = file->f_mapping;
+ struct file *fpin = NULL;
+ pgoff_t offset = vmf->pgoff;
/* If we don't want any read-ahead, don't bother */
- if (vma->vm_flags & VM_RAND_READ)
- return;
+ if (vmf->vma->vm_flags & VM_RAND_READ)
+ return fpin;
if (ra->mmap_miss > 0)
ra->mmap_miss--;
- if (PageReadahead(page))
+ if (PageReadahead(page)) {
+ fpin = maybe_unlock_mmap_for_io(vmf, fpin);
page_cache_async_readahead(mapping, ra, file,
page, offset, ra->ra_pages);
+ }
+ return fpin;
}
/**
@@ -2404,6 +2485,7 @@ int filemap_fault(struct vm_fault *vmf)
{
int error;
struct file *file = vmf->vma->vm_file;
+ struct file *fpin = NULL;
struct address_space *mapping = file->f_mapping;
struct file_ra_state *ra = &file->f_ra;
struct inode *inode = mapping->host;
@@ -2425,23 +2507,26 @@ int filemap_fault(struct vm_fault *vmf)
* We found the page, so try async readahead before
* waiting for the lock.
*/
- do_async_mmap_readahead(vmf->vma, ra, file, page, offset);
+ fpin = do_async_mmap_readahead(vmf, page);
} else if (!page) {
/* No page in the page cache at all */
- do_sync_mmap_readahead(vmf->vma, ra, file, offset);
count_vm_event(PGMAJFAULT);
count_memcg_event_mm(vmf->vma->vm_mm, PGMAJFAULT);
ret = VM_FAULT_MAJOR;
+ fpin = do_sync_mmap_readahead(vmf);
retry_find:
- page = find_get_page(mapping, offset);
- if (!page)
- goto no_cached_page;
+ page = pagecache_get_page(mapping, offset,
+ FGP_CREAT|FGP_FOR_MMAP,
+ vmf->gfp_mask);
+ if (!page) {
+ if (fpin)
+ goto out_retry;
+ return VM_FAULT_OOM;
+ }
}
- if (!lock_page_or_retry(page, vmf->vma->vm_mm, vmf->flags)) {
- put_page(page);
- return ret | VM_FAULT_RETRY;
- }
+ if (!lock_page_maybe_drop_mmap(vmf, page, &fpin))
+ goto out_retry;
/* Did it get truncated? */
if (unlikely(page->mapping != mapping)) {
@@ -2459,6 +2544,16 @@ retry_find:
goto page_not_uptodate;
/*
+ * We've made it this far and we had to drop our mmap_sem, now is the
+ * time to return to the upper layer and have it re-find the vma and
+ * redo the fault.
+ */
+ if (fpin) {
+ unlock_page(page);
+ goto out_retry;
+ }
+
+ /*
* Found the page and have a reference on it.
* We must recheck i_size under page lock.
*/
@@ -2472,30 +2567,6 @@ retry_find:
vmf->page = page;
return ret | VM_FAULT_LOCKED;
-no_cached_page:
- /*
- * We're only likely to ever get here if MADV_RANDOM is in
- * effect.
- */
- error = page_cache_read(file, offset, vmf->gfp_mask);
-
- /*
- * The page we want has now been added to the page cache.
- * In the unlikely event that someone removed it in the
- * meantime, we'll just come back here and read it again.
- */
- if (error >= 0)
- goto retry_find;
-
- /*
- * An error return from page_cache_read can result if the
- * system is low on memory, or a problem occurs while trying
- * to schedule I/O.
- */
- if (error == -ENOMEM)
- return VM_FAULT_OOM;
- return VM_FAULT_SIGBUS;
-
page_not_uptodate:
/*
* Umm, take care of errors if the page isn't up-to-date.
@@ -2504,12 +2575,15 @@ page_not_uptodate:
* and we need to check for errors.
*/
ClearPageError(page);
+ fpin = maybe_unlock_mmap_for_io(vmf, fpin);
error = mapping->a_ops->readpage(file, page);
if (!error) {
wait_on_page_locked(page);
if (!PageUptodate(page))
error = -EIO;
}
+ if (fpin)
+ goto out_retry;
put_page(page);
if (!error || error == AOP_TRUNCATED_PAGE)
@@ -2518,6 +2592,18 @@ page_not_uptodate:
/* Things didn't work out. Return zero to tell the mm layer so. */
shrink_readahead_size_eio(file, ra);
return VM_FAULT_SIGBUS;
+
+out_retry:
+ /*
+ * We dropped the mmap_sem, we need to return to the fault handler to
+ * re-find the vma and come back and find our hopefully still populated
+ * page.
+ */
+ if (page)
+ put_page(page);
+ if (fpin)
+ fput(fpin);
+ return ret | VM_FAULT_RETRY;
}
EXPORT_SYMBOL(filemap_fault);
@@ -2688,7 +2774,7 @@ static struct page *wait_on_page_read(struct page *page)
static struct page *do_read_cache_page(struct address_space *mapping,
pgoff_t index,
- int (*filler)(void *, struct page *),
+ int (*filler)(struct file *, struct page *),
void *data,
gfp_t gfp)
{
@@ -2795,7 +2881,7 @@ out:
*/
struct page *read_cache_page(struct address_space *mapping,
pgoff_t index,
- int (*filler)(void *, struct page *),
+ int (*filler)(struct file *, struct page *),
void *data)
{
return do_read_cache_page(mapping, index, filler, data, mapping_gfp_mask(mapping));
@@ -2817,7 +2903,7 @@ struct page *read_cache_page_gfp(struct address_space *mapping,
pgoff_t index,
gfp_t gfp)
{
- filler_t *filler = (filler_t *)mapping->a_ops->readpage;
+ filler_t *filler = mapping->a_ops->readpage;
return do_read_cache_page(mapping, index, filler, NULL, gfp);
}
@@ -2837,6 +2923,9 @@ inline ssize_t generic_write_checks(struct kiocb *iocb, struct iov_iter *from)
unsigned long limit = rlimit(RLIMIT_FSIZE);
loff_t pos;
+ if (IS_SWAPFILE(inode))
+ return -ETXTBSY;
+
if (!iov_iter_count(from))
return 0;
generated by cgit v1.2.3 (git 2.25.1) at 2024-07-18 10:13:16 +0000