kernel/linux.git/drivers/scsi/sg.c, branch linux-7.1.y

scsi: sg: Don't use GFP_ATOMIC in sg_start_req()

2026-04-21T02:13:41+00:00

sg_start_req() is called from normal user context and can sleep when waiting for memory. Switch it to use GFP_KERNEL, which fixes allocation failures seen with the bio_alloc rework. Fixes: b520c4eef83d ("block: split bio_alloc_bioset more clearly into a fast and slowpath") Reported-by: Shin'ichiro Kawasaki Signed-off-by: Christoph Hellwig Tested-by: Shin'ichiro Kawasaki Reviewed-by: John Garry Reviewed-by: Hannes Reinecke Reviewed-by: Bart Van Assche Link: https://patch.msgid.link/20260415060813.807659-2-hch@lst.de Signed-off-by: Martin K. Petersen

scsi: sg: Remove deprecated sg-big-buff

2026-03-01T01:25:04+00:00

These deprecated sysctl has been broken since commit 26d1c80fd61e ("scsi/sg: move sg-big-buff sysctl to scsi/sg.c") and nobody has found this. I believe it's time to remove it, which will allow us to clean up a significant amount of code. Signed-off-by: Yang Erkun Reviewed-by: Bart Van Assche Link: https://patch.msgid.link/20260127062044.3034148-4-yangerkun@huawei.com Signed-off-by: Martin K. Petersen

scsi: sg: Resolve soft lockup issue when opening /dev/sgX

2026-03-01T01:25:04+00:00

The parameter def_reserved_size defines the default buffer size reserved for each Sg_fd and should be restricted to a range between 0 and 1,048,576 (see https://tldp.org/HOWTO/SCSI-Generic-HOWTO/proc.html). Although the function sg_proc_write_dressz enforces this limit, it is possible to bypass it by directly modifying the module parameter as shown below, which then causes a soft lockup: echo -1 > /sys/module/sg/parameters/def_reserved_size exec 4<> /dev/sg0 watchdog: BUG: soft lockup - CPU#5 stuck for 26 seconds! [bash:537] Modules loaded: CPU: 5 UID: 0 PID: 537 Command: bash, kernel version 6.19.0-rc3+ #134, PREEMPT disabled Hardware: QEMU Standard PC (i440FX + PIIX, 1996), BIOS version 1.16.1-2.fc37 dated 04/01/2014 ... Call Trace: sg_build_reserve+0x5c/0xa0 sg_add_sfp+0x168/0x270 sg_open+0x16e/0x340 chrdev_open+0xbe/0x230 do_dentry_open+0x175/0x480 vfs_open+0x34/0xf0 do_open+0x265/0x3d0 path_openat+0x110/0x290 do_filp_open+0xc3/0x170 do_sys_openat2+0x71/0xe0 __x64_sys_openat+0x6d/0xa0 do_syscall_64+0x62/0x310 entry_SYSCALL_64_after_hwframe+0x76/0x7e The fix is to use module_param_cb to validate and reject invalid values assigned to def_reserved_size. Fixes: 6460e75a104d ("[SCSI] sg: fixes for large page_size") Signed-off-by: Yang Erkun Reviewed-by: Bart Van Assche Link: https://patch.msgid.link/20260127062044.3034148-3-yangerkun@huawei.com Signed-off-by: Martin K. Petersen

scsi: sg: Fix sysctl sg-big-buff register during sg_init()

2026-03-01T01:25:04+00:00

Commit 26d1c80fd61e ("scsi/sg: move sg-big-buff sysctl to scsi/sg.c") made a mistake. sysctl sg-big-buff was not created because the call to register_sg_sysctls() was placed on the wrong code path. Fixes: 26d1c80fd61e ("scsi/sg: move sg-big-buff sysctl to scsi/sg.c") Signed-off-by: Yang Erkun Reviewed-by: Bart Van Assche Link: https://patch.msgid.link/20260127062044.3034148-2-yangerkun@huawei.com Signed-off-by: Martin K. Petersen

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This was done entirely with mindless brute force, using git grep -l '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

block: pass io_comp_batch to rq_end_io_fn callback

2026-01-20T17:12:54+00:00

Add a third parameter 'const struct io_comp_batch *' to the rq_end_io_fn callback signature. This allows end_io handlers to access the completion batch context when requests are completed via blk_mq_end_request_batch(). The io_comp_batch is passed from blk_mq_end_request_batch(), while NULL is passed from __blk_mq_end_request() and blk_mq_put_rq_ref() which don't have batch context. This infrastructure change enables drivers to detect whether they're being called from a batched completion path (like iopoll) and access additional context stored in the io_comp_batch. Update all rq_end_io_fn implementations: - block/blk-mq.c: blk_end_sync_rq - block/blk-flush.c: flush_end_io, mq_flush_data_end_io - drivers/nvme/host/ioctl.c: nvme_uring_cmd_end_io - drivers/nvme/host/core.c: nvme_keep_alive_end_io - drivers/nvme/host/pci.c: abort_endio, nvme_del_queue_end, nvme_del_cq_end - drivers/nvme/target/passthru.c: nvmet_passthru_req_done - drivers/scsi/scsi_error.c: eh_lock_door_done - drivers/scsi/sg.c: sg_rq_end_io - drivers/scsi/st.c: st_scsi_execute_end - drivers/target/target_core_pscsi.c: pscsi_req_done - drivers/md/dm-rq.c: end_clone_request Signed-off-by: Ming Lei Reviewed-by: Kanchan Joshi Signed-off-by: Jens Axboe

scsi: sg: Fix occasional bogus elapsed time that exceeds timeout

2025-12-17T02:24:28+00:00

A race condition was found in sg_proc_debug_helper(). It was observed on a system using an IBM LTO-9 SAS Tape Drive (ULTRIUM-TD9) and monitoring /proc/scsi/sg/debug every second. A very large elapsed time would sometimes appear. This is caused by two race conditions. We reproduced the issue with an IBM ULTRIUM-HH9 tape drive on an x86_64 architecture. A patched kernel was built, and the race condition could not be observed anymore after the application of this patch. A reproducer C program utilising the scsi_debug module was also built by Changhui Zhong and can be viewed here: https://github.com/MichaelRabek/linux-tests/blob/master/drivers/scsi/sg/sg_race_trigger.c The first race happens between the reading of hp->duration in sg_proc_debug_helper() and request completion in sg_rq_end_io(). The hp->duration member variable may hold either of two types of information: #1 - The start time of the request. This value is present while the request is not yet finished. #2 - The total execution time of the request (end_time - start_time). If sg_proc_debug_helper() executes *after* the value of hp->duration was changed from #1 to #2, but *before* srp->done is set to 1 in sg_rq_end_io(), a fresh timestamp is taken in the else branch, and the elapsed time (value type #2) is subtracted from a timestamp, which cannot yield a valid elapsed time (which is a type #2 value as well). To fix this issue, the value of hp->duration must change under the protection of the sfp->rq_list_lock in sg_rq_end_io(). Since sg_proc_debug_helper() takes this read lock, the change to srp->done and srp->header.duration will happen atomically from the perspective of sg_proc_debug_helper() and the race condition is thus eliminated. The second race condition happens between sg_proc_debug_helper() and sg_new_write(). Even though hp->duration is set to the current time stamp in sg_add_request() under the write lock's protection, it gets overwritten by a call to get_sg_io_hdr(), which calls copy_from_user() to copy struct sg_io_hdr from userspace into kernel space. hp->duration is set to the start time again in sg_common_write(). If sg_proc_debug_helper() is called between these two calls, an arbitrary value set by userspace (usually zero) is used to compute the elapsed time. To fix this issue, hp->duration must be set to the current timestamp again after get_sg_io_hdr() returns successfully. A small race window still exists between get_sg_io_hdr() and setting hp->duration, but this window is only a few instructions wide and does not result in observable issues in practice, as confirmed by testing. Additionally, we fix the format specifier from %d to %u for printing unsigned int values in sg_proc_debug_helper(). Signed-off-by: Michal Rábek Suggested-by: Tomas Henzl Tested-by: Changhui Zhong Reviewed-by: Ewan D. Milne Reviewed-by: John Meneghini Reviewed-by: Tomas Henzl Link: https://patch.msgid.link/20251212160900.64924-1-mrabek@redhat.com Signed-off-by: Martin K. Petersen

scsi: sg: Do not sleep in atomic context

2025-11-20T03:46:36+00:00

sg_finish_rem_req() calls blk_rq_unmap_user(). The latter function may sleep. Hence, call sg_finish_rem_req() with interrupts enabled instead of disabled. Reported-by: syzbot+c01f8e6e73f20459912e@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-scsi/691560c4.a70a0220.3124cb.001a.GAE@google.com/ Cc: Hannes Reinecke Cc: stable@vger.kernel.org Fixes: 97d27b0dd015 ("scsi: sg: close race condition in sg_remove_sfp_usercontext()") Signed-off-by: Bart Van Assche Link: https://patch.msgid.link/20251113181643.1108973-1-bvanassche@acm.org Signed-off-by: Martin K. Petersen

scsi: sg: drop nth_page() usage within SG entry

2025-09-21T21:22:08+00:00

It's no longer required to use nth_page() when iterating pages within a single SG entry, so let's drop the nth_page() usage. Link: https://lkml.kernel.org/r/20250901150359.867252-32-david@redhat.com Signed-off-by: David Hildenbrand Reviewed-by: Bart Van Assche Reviewed-by: Lorenzo Stoakes Reviewed-by: Martin K. Petersen Cc: Doug Gilbert Cc: "James E.J. Bottomley" Signed-off-by: Andrew Morton