From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2DECB4AA1EE for ; Thu, 3 Sep 2026 13:06:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788440822; cv=none; b=biTlHY2a1/kEa7mukleFFKOyL1s8e3C02i9GhYXUZzmg3E6iF0igtLQdJb/Jhdwp2uIChq936gXyLbO9wp5nEdqK2qwvn/Ev2/BrZkbxFUTHMPExZZFkDIIBpXdAr7+2dC+2E823ULgna+acH5FQ9EWD8kpQA89TcaIOSt0qfng= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788440822; c=relaxed/simple; bh=LPyhXOjCtDbRNZOOkhSU0QLSGWnrETyUOKKMMkjwcI4=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=l55QavKbfXsppU6bE0X0cvgYZk97Ns+uQPpdMwvBAocjWoEn1kqXy8AaUblGGe8hbzOMm7hSSBJfZrGjAW0FsCu4RylJiwnMUJYqu9QyJbAhj+pFe/D/HFlIYlJSnxs5rHl6oQA+yazAzWHxjCbNa6O+PiiTMADQdI8cDFBPbZ4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=zDmlI18h; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="zDmlI18h" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 920EE1F00A3F; Thu, 3 Sep 2026 13:06:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788440816; bh=1xpMO83OlC8YOzX6Ngpfq4XOOE+Wzhqa65GaU+m4tio=; h=Subject:To:Cc:From:Date; b=zDmlI18hNh8Lg6wAgPi0oPQdVfUFScMdg7ph1hgYp/uQFHzAhTr1N8U2Lo43g5jbe jwLYPEbxzv8qjEBx0edWSxc4Kjn3Hnal0OvRhx4LT/8WuDuivWYIoqd8zxSJAusXDr WG7elVCBHD+OSMYaIhndYIL1c5rmV4xkYbWB4/N0= Subject: FAILED: patch "[PATCH] zram: fix slot lock bit position on big-endian 64-bit" failed to apply to 7.2-stable tree To: devnexen@gmail.com,akpm@linux-foundation.org,minchan@kernel.org,senozhatsky@chromium.org,stable@vger.kernel.org Cc: From: Date: Thu, 03 Sep 2026 15:01:37 +0200 Message-ID: <2026090337-onshore-thermos-9127@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 7.2-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 . 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-7.2.y git checkout FETCH_HEAD git cherry-pick -x a8b5875741d416703e19ad8eeac6fce8a12bd6e4 # git commit -s git send-email --to '' --in-reply-to '2026090337-onshore-thermos-9127@gregkh' --subject-prefix 'PATCH 7.2.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From a8b5875741d416703e19ad8eeac6fce8a12bd6e4 Mon Sep 17 00:00:00 2001 From: David Carlier Date: Mon, 10 Aug 2026 21:22:37 +0100 Subject: [PATCH] zram: fix slot lock bit position on big-endian 64-bit The slot lock is a bit operation on the whole __lock word, which flags and ac_time alias as two u32s. On little-endian the lock bit lands in the position ZRAM_ENTRY_LOCK reserves in flags, so the aliasing works out. On 64-bit big-endian it lands in ac_time instead: with ZRAM_TRACK_ENTRY_ACTIME enabled, storing the access time from mark_slot_accessed() or slot_free() wipes out the held lock bit, letting another CPU take the same slot lock; an access time value with that bit set makes the slot look locked forever. Shift the lock bit into the flags half of the word on big-endian 64-bit. Link: https://lore.kernel.org/20260810202241.2436603-1-devnexen@gmail.com Fixes: 2e8ff2f51dde ("zram: use u32 for entry ac_time tracking") Signed-off-by: David Carlier Reviewed-by: Sergey Senozhatsky Cc: Minchan Kim Cc: Signed-off-by: Andrew Morton diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index d09fdca49cbd..a9b3bb1d3bef 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -74,7 +74,7 @@ static __must_check bool slot_trylock(struct zram *zram, unsigned long index) { unsigned long *lock = &zram->table[index].__lock; - if (!test_and_set_bit_lock(ZRAM_ENTRY_LOCK, lock)) { + if (!test_and_set_bit_lock(ZRAM_ENTRY_LOCK_BIT, lock)) { mutex_acquire(&zram->table_lock_map, 0, 1, _RET_IP_); lock_acquired(&zram->table_lock_map, _RET_IP_); return true; @@ -88,7 +88,7 @@ static void slot_lock(struct zram *zram, unsigned long index) unsigned long *lock = &zram->table[index].__lock; mutex_acquire(&zram->table_lock_map, 0, 0, _RET_IP_); - wait_on_bit_lock(lock, ZRAM_ENTRY_LOCK, TASK_UNINTERRUPTIBLE); + wait_on_bit_lock(lock, ZRAM_ENTRY_LOCK_BIT, TASK_UNINTERRUPTIBLE); lock_acquired(&zram->table_lock_map, _RET_IP_); } @@ -97,7 +97,7 @@ static void slot_unlock(struct zram *zram, unsigned long index) unsigned long *lock = &zram->table[index].__lock; mutex_release(&zram->table_lock_map, _RET_IP_); - clear_and_wake_up_bit(ZRAM_ENTRY_LOCK, lock); + clear_and_wake_up_bit(ZRAM_ENTRY_LOCK_BIT, lock); } static inline bool init_done(struct zram *zram) diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h index 4fddc582f3b8..7a55d751417e 100644 --- a/drivers/block/zram/zram_drv.h +++ b/drivers/block/zram/zram_drv.h @@ -15,6 +15,7 @@ #ifndef _ZRAM_DRV_H_ #define _ZRAM_DRV_H_ +#include #include #include @@ -57,6 +58,19 @@ enum zram_pageflags { __NR_ZRAM_PAGEFLAGS, }; +/* + * The slot lock is a bit-wait lock on the whole __lock word, while + * flags and ac_time alias that word as two u32s. The lock bit must + * land in the slot that ZRAM_ENTRY_LOCK reserves in attr.flags; on + * 64-bit big-endian the flags word maps to the upper half of __lock, + * so the bit position has to be shifted up. + */ +#if defined(CONFIG_64BIT) && defined(__BIG_ENDIAN) +#define ZRAM_ENTRY_LOCK_BIT (ZRAM_ENTRY_LOCK + 32) +#else +#define ZRAM_ENTRY_LOCK_BIT ZRAM_ENTRY_LOCK +#endif + /* * Allocated for each disk page. We use bit-lock (ZRAM_ENTRY_LOCK bit * of flags) to save memory. There can be plenty of entries and standard