FAILED: patch "[PATCH] erofs: skip sufficiently large global buffers when resizing" failed to apply to 6.18-stable tree

FAILED: patch "[PATCH] erofs: skip sufficiently large global buffers when resizing" failed to apply to 6.18-stable tree

[gregkh]

The patch below does not apply to the 6.18-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y
git checkout FETCH_HEAD
git cherry-pick -x a7d097cf01301c5da37927c8f26123d006f0fd8a
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026090345-used-spearfish-a45c@gregkh' --subject-prefix 'PATCH 6.18.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From a7d097cf01301c5da37927c8f26123d006f0fd8a Mon Sep 17 00:00:00 2001
From: Nikhil Gurudasani <nikhilgurudasani314@gmail.com>
Date: Sat, 22 Aug 2026 19:30:17 +0530
Subject: [PATCH] erofs: skip sufficiently large global buffers when resizing

z_erofs_gbuf_nrpages is advanced only after every global buffer has been
grown. If a resize fails after some buffers were enlarged, a retry
revisits those enlarged buffers.

Retrying the same size then returns -ENOMEM because alloc_pages_bulk()
has no pages to add and the unchanged return value is treated as a
failure. Retrying an intermediate size allocates a temporary pointer
array smaller than gbuf->nrpages and copies more existing pointers than
the array can hold.

Skip buffers that already satisfy the request. Once all remaining
buffers have caught up, advancing z_erofs_gbuf_nrpages again describes
the guaranteed minimum size across the pool.

Fixes: d6db47e571dc ("erofs: do not use pagepool in z_erofs_gbuf_growsize()")
Cc: stable@vger.kernel.org # 6.10+
Signed-off-by: Nikhil Gurudasani <nikhilgurudasani314@gmail.com>
Reviewed-by: Gao Xiang <xiang@kernel.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <xiang@kernel.org>

diff --git a/fs/erofs/zutil.c b/fs/erofs/zutil.c
index a0ce9226bc02..6b9bfa2ef3b6 100644
--- a/fs/erofs/zutil.c
+++ b/fs/erofs/zutil.c
@@ -79,6 +79,8 @@ int z_erofs_gbuf_growsize(unsigned int nrpages)
 
 	for (i = 0; i < z_erofs_gbuf_count; ++i) {
 		gbuf = &z_erofs_gbufpool[i];
+		if (gbuf->nrpages >= nrpages)
+			continue;
 		tmp_pages = kzalloc_objs(*tmp_pages, nrpages);
 		if (!tmp_pages)
 			goto out;

[PATCH 6.18.y] erofs: skip sufficiently large global buffers when resizing

[Sasha Levin]

From: Nikhil Gurudasani <nikhilgurudasani314@gmail.com>

[ Upstream commit a7d097cf01301c5da37927c8f26123d006f0fd8a ]

z_erofs_gbuf_nrpages is advanced only after every global buffer has been
grown. If a resize fails after some buffers were enlarged, a retry
revisits those enlarged buffers.

Retrying the same size then returns -ENOMEM because alloc_pages_bulk()
has no pages to add and the unchanged return value is treated as a
failure. Retrying an intermediate size allocates a temporary pointer
array smaller than gbuf->nrpages and copies more existing pointers than
the array can hold.

Skip buffers that already satisfy the request. Once all remaining
buffers have caught up, advancing z_erofs_gbuf_nrpages again describes
the guaranteed minimum size across the pool.

Fixes: d6db47e571dc ("erofs: do not use pagepool in z_erofs_gbuf_growsize()")
Cc: stable@vger.kernel.org # 6.10+
Signed-off-by: Nikhil Gurudasani <nikhilgurudasani314@gmail.com>
Reviewed-by: Gao Xiang <xiang@kernel.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <xiang@kernel.org>
[ preserved the existing kcalloc() allocation instead of upstream kzalloc_objs() ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/erofs/zutil.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/erofs/zutil.c b/fs/erofs/zutil.c
index 55ff2ab5128e0..54ce492e897f3 100644
--- a/fs/erofs/zutil.c
+++ b/fs/erofs/zutil.c
@@ -79,6 +79,8 @@ int z_erofs_gbuf_growsize(unsigned int nrpages)
 
 	for (i = 0; i < z_erofs_gbuf_count; ++i) {
 		gbuf = &z_erofs_gbufpool[i];
+		if (gbuf->nrpages >= nrpages)
+			continue;
 		tmp_pages = kcalloc(nrpages, sizeof(*tmp_pages), GFP_KERNEL);
 		if (!tmp_pages)
 			goto out;
-- 
2.53.0