Hi Greg,
On 2025/7/15 21:13, Greg Kroah-Hartman wrote:
6.12-stable review patch. If anyone has any objections, please let me know.
Can we drop this patch?
Since it's a new feature and lack of another fix backport: commit b10a1e5643e5 ("erofs: fix rare pcluster memory leak after unmounting")
It's not worth to backport those commits in order to backport a simple tracepoint fix.
Thanks, Gao Xiang
From: Chunhai Guo guochunhai@vivo.com
[ Upstream commit f5ad9f9a603f829d11ca31a0a4049e16091e8c13 ]
Once a pcluster is fully decompressed and there are no attached cached folios, its corresponding `struct z_erofs_pcluster` will be freed. This will significantly reduce the frequency of calls to erofs_shrink_scan() and the memory allocated for `struct z_erofs_pcluster`.
The tables below show approximately a 96% reduction in the calls to erofs_shrink_scan() and in the memory allocated for `struct z_erofs_pcluster` after applying this patch. The results were obtained by performing a test to copy a 4.1GB partition on ARM64 Android devices running the 6.6 kernel with an 8-core CPU and 12GB of memory.
- The reduction in calls to erofs_shrink_scan():
+-----------------+-----------+----------+---------+ | | w/o patch | w/ patch | diff | +-----------------+-----------+----------+---------+ | Average (times) | 11390 | 390 | -96.57% | +-----------------+-----------+----------+---------+
- The reduction in memory released by erofs_shrink_scan():
+-----------------+-----------+----------+---------+ | | w/o patch | w/ patch | diff | +-----------------+-----------+----------+---------+ | Average (Byte) | 133612656 | 4434552 | -96.68% | +-----------------+-----------+----------+---------+
Signed-off-by: Chunhai Guo guochunhai@vivo.com Reviewed-by: Gao Xiang hsiangkao@linux.alibaba.com Link: https://lore.kernel.org/r/20241112043235.546164-1-guochunhai@vivo.com Signed-off-by: Gao Xiang hsiangkao@linux.alibaba.com Stable-dep-of: d53238b614e0 ("erofs: fix to add missing tracepoint in erofs_readahead()") Signed-off-by: Sasha Levin sashal@kernel.org
fs/erofs/zdata.c | 57 ++++++++++++++++++++++++++++++++---------------- 1 file changed, 38 insertions(+), 19 deletions(-)
diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c index 6b1d19d1d2f0c..4d5a1fbd7e0ad 100644 --- a/fs/erofs/zdata.c +++ b/fs/erofs/zdata.c @@ -882,14 +882,11 @@ static void z_erofs_rcu_callback(struct rcu_head *head) struct z_erofs_pcluster, rcu)); } -static bool erofs_try_to_release_pcluster(struct erofs_sb_info *sbi, +static bool __erofs_try_to_release_pcluster(struct erofs_sb_info *sbi, struct z_erofs_pcluster *pcl) {
- int free = false;
- spin_lock(&pcl->lockref.lock); if (pcl->lockref.count)
goto out;
return false;/* * Note that all cached folios should be detached before deleted from @@ -897,7 +894,7 @@ static bool erofs_try_to_release_pcluster(struct erofs_sb_info *sbi, * orphan old pcluster when the new one is available in the tree. */ if (erofs_try_to_free_all_cached_folios(sbi, pcl))
goto out;
return false;/* * It's impossible to fail after the pcluster is freezed, but in order @@ -906,8 +903,16 @@ static bool erofs_try_to_release_pcluster(struct erofs_sb_info *sbi, DBG_BUGON(__xa_erase(&sbi->managed_pslots, pcl->index) != pcl); lockref_mark_dead(&pcl->lockref);
- free = true;
-out:
- return true;
+}
+static bool erofs_try_to_release_pcluster(struct erofs_sb_info *sbi,
struct z_erofs_pcluster *pcl)+{
- bool free;
- spin_lock(&pcl->lockref.lock);
- free = __erofs_try_to_release_pcluster(sbi, pcl); spin_unlock(&pcl->lockref.lock); if (free) { atomic_long_dec(&erofs_global_shrink_cnt);
@@ -938,16 +943,25 @@ unsigned long z_erofs_shrink_scan(struct erofs_sb_info *sbi, return freed; } -static void z_erofs_put_pcluster(struct z_erofs_pcluster *pcl) +static void z_erofs_put_pcluster(struct erofs_sb_info *sbi,
struct z_erofs_pcluster *pcl, bool try_free)- bool free = false;
- if (lockref_put_or_lock(&pcl->lockref)) return;
DBG_BUGON(__lockref_is_dead(&pcl->lockref));
- if (pcl->lockref.count == 1)
atomic_long_inc(&erofs_global_shrink_cnt);- --pcl->lockref.count;
- if (!--pcl->lockref.count) {
if (try_free && xa_trylock(&sbi->managed_pslots)) {free = __erofs_try_to_release_pcluster(sbi, pcl);xa_unlock(&sbi->managed_pslots);}atomic_long_add(!free, &erofs_global_shrink_cnt);- } spin_unlock(&pcl->lockref.lock);
- if (free)
call_rcu(&pcl->rcu, z_erofs_rcu_callback);static void z_erofs_pcluster_end(struct z_erofs_decompress_frontend *fe) @@ -968,7 +982,7 @@ static void z_erofs_pcluster_end(struct z_erofs_decompress_frontend *fe) * any longer if the pcluster isn't hosted by ourselves. */ if (fe->mode < Z_EROFS_PCLUSTER_FOLLOWED_NOINPLACE)
z_erofs_put_pcluster(pcl);
z_erofs_put_pcluster(EROFS_I_SB(fe->inode), pcl, false);fe->pcl = NULL; } @@ -1271,6 +1285,7 @@ static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be, int i, j, jtop, err2; struct page *page; bool overlapped;
- bool try_free = true;
mutex_lock(&pcl->lock); be->nr_pages = PAGE_ALIGN(pcl->length + pcl->pageofs_out) >> PAGE_SHIFT; @@ -1328,9 +1343,12 @@ static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be, /* managed folios are still left in compressed_bvecs[] */ for (i = 0; i < pclusterpages; ++i) { page = be->compressed_pages[i];
if (!page ||erofs_folio_is_managed(sbi, page_folio(page)))
if (!page) continue;if (erofs_folio_is_managed(sbi, page_folio(page))) {try_free = false;continue;} (void)z_erofs_put_shortlivedpage(be->pagepool, page); WRITE_ONCE(pcl->compressed_bvecs[i].page, NULL);@@ -1375,6 +1393,11 @@ static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be, /* pcluster lock MUST be taken before the following line */ WRITE_ONCE(pcl->next, Z_EROFS_PCLUSTER_NIL); mutex_unlock(&pcl->lock);
- if (z_erofs_is_inline_pcluster(pcl))
z_erofs_free_pcluster(pcl);- else
z_erofs_put_pcluster(sbi, pcl, try_free);@@ -1397,10 +1420,6 @@ static int z_erofs_decompress_queue(const struct z_erofs_decompressqueue *io, owned = READ_ONCE(be.pcl->next); err = z_erofs_decompress_pcluster(&be, err) ?: err;
if (z_erofs_is_inline_pcluster(be.pcl))z_erofs_free_pcluster(be.pcl);elsez_erofs_put_pcluster(be.pcl);