kernel/git/stable/linux.git/drivers/block/zram, branch master

zram: fix slot lock bit position on big-endian 64-bit

2026-08-25T01:43:19+00:00

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

zram: switch to unsigned long indexing

2026-08-25T01:43:06+00:00

zram has always used "unsigned int" for (page) index calculations, which unnecessarily limited max zram disksize. Switch to "unsigned long" and permit much larger zram devices. Link: https://lore.kernel.org/20260806031640.536615-1-senozhatsky@chromium.org Signed-off-by: Sergey Senozhatsky Suggested-by: Andrew Morton Co-developed-by: Longlong Xia Cc: Minchan Kim Signed-off-by: Andrew Morton

zram: fix out-of-bounds access in read_block_state()

2026-08-25T01:43:05+00:00

read_block_state() calculates nr_pages before taking dev_lock. If the device is reset and reinitialized with a smaller disksize before lock acquisition, nr_pages still describes the old table. The subsequent loop can then call slot_lock() past the end of the newly allocated table. Read disksize after acquiring dev_lock and checking that the device is initialized. The read lock then keeps the table and its bound stable for the duration of the scan. Link: https://lore.kernel.org/20260804065919.3970386-3-xialonglong2025@163.com Fixes: c0265342bff4 ("zram: introduce zram memory tracking") Assisted-by: Codex:gpt-5.6-sol Signed-off-by: Longlong Xia Reviewed-by: Sergey Senozhatsky Cc: Jens Axboe Cc: Minchan Kim Cc: Signed-off-by: Andrew Morton

zram: fix out-of-bounds access in writeback_store()

2026-08-25T01:43:05+00:00

Patch series "zram: fix stale scan bounds after reinitialization". Both writeback_store() and read_block_state() derive their table scan bounds from zram->disksize before acquiring dev_lock. If the device is reset and reinitialized with a smaller disksize between that read and lock acquisition, the bound can describe the old table while the scan operates on the new one. This can lead to out-of-bounds slot accesses. Move both bound calculations under dev_lock so each bound remains consistent with the table throughout its scan. Keep the fixes separate because the affected interfaces originate from different commits and can be backported independently. This patch (of 2): writeback_store() calculates the table scan bounds before taking dev_lock. A reset followed by reconfiguration with a smaller disksize can therefore replace zram->table while writeback_store() is waiting for the lock. Once it acquires the lock, it sees an initialized device but scans the new table using the old upper bound, resulting in an out-of-bounds access. Calculate the number of pages while holding dev_lock so the scan bound matches the table protected by the lock. Link: https://lore.kernel.org/20260804065919.3970386-1-xialonglong2025@163.com Link: https://lore.kernel.org/20260804065919.3970386-2-xialonglong2025@163.com Fixes: a939888ec38b ("zram: support idle/huge page writeback") Assisted-by: Codex:gpt-5.6-sol Signed-off-by: Longlong Xia Reviewed-by: Sergey Senozhatsky Cc: Jens Axboe Cc: Minchan Kim Cc: Signed-off-by: Andrew Morton

zram: reset per-priority params when changing algorithm before init

2026-08-25T01:43:05+00:00

Parameters validated against one algorithm may be invalid for another (e.g. lz4 accepts level=65535 but zstd does not). Although algorithm changes are blocked after disksize is set, they are allowed before device initialization. Reset per-priority params on algorithm change so that stale parameters do not silently carry over. Link: https://lore.kernel.org/20260804093841.67920-6-haoqinhuang7@gmail.com Signed-off-by: Haoqin Huang Signed-off-by: Rongwei Wang Reviewed-by: Sergey Senozhatsky Tested-by: Sergey Senozhatsky Cc: David Sterba Cc: Jens Axboe Cc: Minchan Kim Cc: Nick Terrell Signed-off-by: Andrew Morton

zram: validate parameters in each backend's setup_params

2026-08-25T01:43:04+00:00

Dict and level parameters are silently accepted even for backends that do not support them. Validate these parameters in each backend's .setup_params() to reject unsupported combinations and out-of-range levels with a specific error message. Link: https://lore.kernel.org/20260804093841.67920-5-haoqinhuang7@gmail.com Signed-off-by: Haoqin Huang Signed-off-by: Rongwei Wang Reviewed-by: Sergey Senozhatsky Tested-by: Sergey Senozhatsky Cc: David Sterba Cc: Jens Axboe Cc: Minchan Kim Cc: Nick Terrell Signed-off-by: Andrew Morton

zram: add pr_fmt to backend files

2026-08-25T01:43:04+00:00

Add pr_fmt to each backend so that pr_err() messages are auto-prefixed with the algorithm name. While at it, tweak the deflate winbits pr_err to avoid a duplicated "deflate" prefix. Link: https://lore.kernel.org/20260804093841.67920-4-haoqinhuang7@gmail.com Signed-off-by: Haoqin Huang Signed-off-by: Rongwei Wang Reviewed-by: Sergey Senozhatsky Tested-by: Sergey Senozhatsky Cc: David Sterba Cc: Jens Axboe Cc: Minchan Kim Cc: Nick Terrell Signed-off-by: Andrew Morton

zram: reject zero-size dictionary

2026-08-25T01:43:04+00:00

kernel_read_file_from_path() already rejects empty files (i_size <= 0) and returns -EINVAL, but the current implementation only checks for sz < 0 without logging any information. Use sz == 0 to reject the zero-size case and print distinct error messages for each failure type. Link: https://lore.kernel.org/20260804093841.67920-3-haoqinhuang7@gmail.com Signed-off-by: Haoqin Huang Signed-off-by: Rongwei Wang Reviewed-by: Sergey Senozhatsky Tested-by: Sergey Senozhatsky Cc: David Sterba Cc: Jens Axboe Cc: Minchan Kim Cc: Nick Terrell Signed-off-by: Andrew Morton

zram: do not release zstd global params from error paths

2026-08-25T01:43:04+00:00

Patch series "zram: fix zstd error paths and add parameter validation", v6, Patch 1 removes zstd_release_params() from both zstd_create() and zstd_setup_params() error paths -- the former is a layering violation in a per-CPU callback, the latter is redundant as zcomp_init() already calls release_params() on setup failure. Patch 2 rejects zero-size dictionaries and prints distinct error messages for sz < 0 (returns the original error code) and sz == 0 ("empty file"). Currently errors are silently swallowed. Patch 3 adds pr_fmt to each backend file so that pr_err() messages are auto-prefixed with the algorithm name. Patch 4 validates dict and level parameters in each backend's .setup_params(), rejecting unsupported combinations and out-of-range levels. Patch 5 resets per-priority params on algorithm change before init. This patch (of 5): zstd_setup_params() creates global cdict and ddict stored in params->drv_data, shared across all per-CPU contexts. The per-CPU zstd_create() error path called zstd_release_params(), which freed those globally-shared objects. This is a layering violation: a per-CPU callback should only clean up its own context, not release resources owned by the compression lifecycle. zstd_setup_params() called zstd_release_params() on its own error path as well, but zcomp_init() already calls release_params() when setup fails, so this is redundant. Remove zstd_release_params() from both error paths. Link: https://lore.kernel.org/20260804093841.67920-1-haoqinhuang7@gmail.com Link: https://lore.kernel.org/20260804093841.67920-2-haoqinhuang7@gmail.com Signed-off-by: Haoqin Huang Signed-off-by: Rongwei Wang Reviewed-by: Sergey Senozhatsky Tested-by: Sergey Senozhatsky Cc: David Sterba Cc: Jens Axboe Cc: Minchan Kim Cc: Nick Terrell Signed-off-by: Andrew Morton

zram: validate deflate params

2026-08-25T01:42:56+00:00

We must validate user-supplied deflate winbits before we pass it to zlib_deflate_workspacesize(), which triggers BUG_ON() if winbits value is outside of valid ranges. Link: https://lore.kernel.org/20260729045745.775973-3-senozhatsky@chromium.org Fixes: dc75a0d93bd5 ("zram: support deflate-specific params") Link: https://sashiko.dev/#/patchset/20260728092935.31139-1-haoqinhuang7@gmail.com Signed-off-by: Sergey Senozhatsky Cc: Minchan Kim Cc: Haoqin Huang Cc: Signed-off-by: Andrew Morton