FAILED: patch "[PATCH] zram: free secondary algorithms names" failed to apply to 6.6-stable tree

The patch below does not apply to the 6.6-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 <[email protected]>.

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-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 684826f8271ad97580b138b9ffd462005e470b99
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024100724-used-ventricle-7559@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

684826f8271a ("zram: free secondary algorithms names")
f2bac7ad187d ("zram: introduce zcomp_params structure")
1d3100cf148d ("zram: add 842 compression backend support")
84112e314f69 ("zram: add zlib compression backend support")
dbf2763cec21 ("zram: pass estimated src size hint to zstd")
73e7d81abbc8 ("zram: add zstd compression backend support")
c60a4ef54446 ("zram: add lz4hc compression backend support")
22d651c3b339 ("zram: add lz4 compression backend support")
2152247c55b6 ("zram: add lzo and lzorle compression backends support") 917a59e81c34 ("zram: introduce custom comp backends API")
04cb7502a5d7 ("zsmalloc: use all available 24 bits of page_type") 43d746dc49bb ("mm/zsmalloc: use a proper page type")
8db00ad56461 ("mm: allow reuse of the lower 16 bit of the page type with an actual type") 6d21dde7adc0 ("mm: update _mapcount and page_type documentation") ff202303c398 ("mm: convert page type macros to enum")
46df8e73a4a3 ("mm: free up PG_slab")
d99e3140a4d3 ("mm: turn folio_test_hugetlb into a PageType")
fd1a745ce03e ("mm: support page_mapcount() on page_has_type() pages") 29cfe7556bfd ("mm: constify more page/folio tests")
443cbaf9e2fd ("crash: split vmcoreinfo exporting code out from crash_core.c")

thanks,

greg k-h

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

From 684826f8271ad97580b138b9ffd462005e470b99 Mon Sep 17 00:00:00 2001
From: Sergey Senozhatsky <[email protected]>
Date: Wed, 11 Sep 2024 11:54:56 +0900
Subject: [PATCH] zram: free secondary algorithms names

We need to kfree() secondary algorithms names when reset zram device that had multi-streams, otherwise we leak memory.

index 1f1bf175a6c3..0207a7fc0a97 100644
@@ -2112,6 +2112,11 @@ static void zram_destroy_comps(struct zram *zram)
 		zram->num_active_comps--;
 	}
 
+	for (prio = ZRAM_SECONDARY_COMP; prio < ZRAM_MAX_COMPS; prio++) {
+		kfree(zram->comp_algs[prio]);
+		zram->comp_algs[prio] = NULL;
+	}
+
 	zram_comp_params_reset(zram);
 }
 

We need to kfree() secondary algorithms names when reset zram device that had multi-streams, otherwise we leak memory.

---
 drivers/block/zram/zram_drv.c | 5 +++++
 1 file changed, 5 insertions(+)

index 06673c6ca255..db729035fd6b 100644
@@ -1983,6 +1983,11 @@ static void zram_destroy_comps(struct zram *zram)
 		zcomp_destroy(comp);
 		zram->num_active_comps--;
 	}
+
+	for (prio = ZRAM_SECONDARY_COMP; prio < ZRAM_MAX_COMPS; prio++) {
+		kfree(zram->comp_algs[prio]);
+		zram->comp_algs[prio] = NULL;
+	}
 }
 
 static void zram_reset_device(struct zram *zram)

2.47.0.rc0.187.ge670bccf7e-goog

From: Andrey Skvortsov <[email protected]>

When CONFIG_ZRAM_MULTI_COMP isn't set ZRAM_SECONDARY_COMP can hold default_compressor, because it's the same offset as ZRAM_PRIMARY_COMP, so we need to make sure that we don't attempt to kfree() the statically defined compressor name.

This is detected by KASAN.

==================================================================

  Call trace:
   kfree+0x60/0x3a0
   zram_destroy_comps+0x98/0x198 [zram]
   zram_reset_device+0x22c/0x4a8 [zram]
   reset_store+0x1bc/0x2d8 [zram]
   dev_attr_store+0x44/0x80
   sysfs_kf_write+0xfc/0x188
   kernfs_fop_write_iter+0x28c/0x428
   vfs_write+0x4dc/0x9b8
   ksys_write+0x100/0x1f8
   __arm64_sys_write+0x74/0xb8
   invoke_syscall+0xd8/0x260
   el0_svc_common.constprop.0+0xb4/0x240
   do_el0_svc+0x48/0x68
   el0_svc+0x40/0xc8
   el0t_64_sync_handler+0x120/0x130
   el0t_64_sync+0x190/0x198
==================================================================

---
 drivers/block/zram/zram_drv.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

index db729035fd6b..606f388c7a57 100644
@@ -1984,8 +1984,10 @@ static void zram_destroy_comps(struct zram *zram)
 		zram->num_active_comps--;
 	}
 
-	for (prio = ZRAM_SECONDARY_COMP; prio < ZRAM_MAX_COMPS; prio++) {
-		kfree(zram->comp_algs[prio]);
+	for (prio = ZRAM_PRIMARY_COMP; prio < ZRAM_MAX_COMPS; prio++) {
+		/* Do not free statically defined compression algorithms */
+		if (zram->comp_algs[prio] != default_compressor)
+			kfree(zram->comp_algs[prio]);
 		zram->comp_algs[prio] = NULL;
 	}
 }

2.47.0.rc0.187.ge670bccf7e-goog