Repository navigation
fs: don't lose inodes that another LRU walker is isolating - #2812
Open
vfsci-bot[bot] wants to merge 1 commit into
Open
vfsci-bot[bot] wants to merge 1 commit into
vfsci-bot[bot] wants to merge 1 commit into
Conversation
When inode_lru_isolate() finds an unused inode that still has page cache, it sets I_LRU_ISOLATING, drops i_lock and the list_lru lock, invalidates the page cache, clears the flag again and returns LRU_RETRY so that the restarted walk can free the inode. Another walker of the same list can reach the inode in that window. It sees a non-zero i_state and takes the inode off the LRU, as it would an inode that is in use. Page cache deletion requeues the inode once the mapping is shrinkable, so this is harmless if it happens before the last deletion. If it happens after, nothing puts the inode back: it stays in memory, unused, clean and without page cache, out of reach of the shrinker and of drop_caches, until it is looked up again or the filesystem is unmounted. Before commit 2a06298 ("vfs: Don't evict inode under the inode lru traversing context") the pin was an i_count reference, and the final iput() put the inode back on the LRU. Skip inodes that are being isolated and leave them to the walker that pinned them, which restarts its walk once it has unpinned them. The window is reached by any unused inode with page cache on CONFIG_HIGHMEM kernels, and otherwise by inodes whose page cache is a single shadow entry at index 0. On an i386 HIGHMEM guest, eight concurrent "echo 2 > /proc/sys/vm/drop_caches" over 2000 freshly read one-page ext4 files leave roughly 400 of the inodes off the LRU per round; on x86_64, with the files' pages first evicted through memory.reclaim, 3 to 4 per round. With this patch, none in either case. Fixes: 2a06298 ("vfs: Don't evict inode under the inode lru traversing context") Cc: stable@vger.kernel.org Assisted-by: LLM Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Series: https://patchwork.kernel.org/project/linux-fsdevel/list/?series=1182493
Submitter: Nikolaos Karaolidis
Version: 1
Patches: 1/1
Message-ID:
<20261009142431.713875-1-nick@karaolidis.com>Base: vfs.base.ci
Lore: https://lore.kernel.org/linux-fsdevel/20261009142431.713875-1-nick@karaolidis.com
Automated by ml2pr