From: Christoph Hellwig hch@lst.de
mainline inclusion from mainline-v6.9-rc1 commit c2dc7e5589a19cff8147f27d4beef7fc0aec2f86 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I9DN5Z CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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The iomap writepage implementation has been removed in commit 478af190cb6c ("iomap: remove iomap_writepage") and this code is now only called through ->writepages which never happens from memory reclaim.
Nove the check from iomap_do_writepage to iomap_writepages so that is only called once per ->writepage invocation.
Signed-off-by: Christoph Hellwig hch@lst.de Link: https://lore.kernel.org/r/20231207072710.176093-5-hch@lst.de Signed-off-by: Christian Brauner brauner@kernel.org Signed-off-by: Zhang Yi yi.zhang@huawei.com --- fs/iomap/buffered-io.c | 24 ++++++++---------------- 1 file changed, 8 insertions(+), 16 deletions(-)
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index e7426fb03325..55da1c0ca608 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -1899,20 +1899,6 @@ static int iomap_do_writepage(struct folio *folio,
trace_iomap_writepage(inode, folio_pos(folio), folio_size(folio));
- /* - * Refuse to write the folio out if we're called from reclaim context. - * - * This avoids stack overflows when called from deeply used stacks in - * random callers for direct reclaim or memcg reclaim. We explicitly - * allow reclaim from kswapd as the stack usage there is relatively low. - * - * This should never happen except in the case of a VM regression so - * warn about it. - */ - if (WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD)) == - PF_MEMALLOC)) - goto redirty; - /* * Is this folio beyond the end of the file? * @@ -1978,8 +1964,6 @@ static int iomap_do_writepage(struct folio *folio,
return iomap_writepage_map(wpc, wbc, inode, folio, end_pos);
-redirty: - folio_redirty_for_writepage(wbc, folio); unlock: folio_unlock(folio); return 0; @@ -1992,6 +1976,14 @@ iomap_writepages(struct address_space *mapping, struct writeback_control *wbc, { int ret;
+ /* + * Writeback from reclaim context should never happen except in the case + * of a VM regression so warn about it and refuse to write the data. + */ + if (WARN_ON_ONCE((current->flags & (PF_MEMALLOC | PF_KSWAPD)) == + PF_MEMALLOC)) + return -EIO; + wpc->ops = ops; ret = write_cache_pages(mapping, wbc, iomap_do_writepage, wpc); if (!wpc->ioend)